Critical Reasoning

In order to withstand tidal currents, juvenile horseshoe crabs frequently burrow in the sand. Such burrowing
discourages barnacles from clinging to their shells. When fully grown, however, the crabs can readily withstand
tidal currents without burrowing, and thus they acquire substantial populations of barnacles. Surprisingly, in
areas where tidal currents are very weak, juvenile horseshoe crabs are found not to have signi�cant barnacle
populations, even though they seldom burrow.
Which of the following, if true, most helps to explain the surprising �nding?
(A) Tidal currents do not themselves dislodge barnacles from the shells of horseshoe crabs.
(B) Barnacles most readily attach themselves to horseshoe crabs in areas where tidal currents are weakest.
(C) The strength of the tidal currents in a given location varies widely over the course of a day.
(D) A very large barnacle population can signi�cantly decrease the ability of a horseshoe crab to � nd food.
(E) Until they are fully grown, horseshoe crabs shed their shells and grow new ones several times a year.
I have some questions about this one. First, can someone explain the meaning of choice A? Themselves refers to what? Also, about choice D, I am also a little confused the meaning it wants to transfer. Can someone explain it?
Thanks in advance!

Crystal W wrote:In order to withstand tidal currents, juvenile horseshoe crabs frequently burrow in the sand. Such burrowing
discourages barnacles from clinging to their shells. When fully grown, however, the crabs can readily withstand
tidal currents without burrowing, and thus they acquire substantial populations of barnacles. Surprisingly, in
areas where tidal currents are very weak, juvenile horseshoe crabs are found not to have signi�cant barnacle
populations, even though they seldom burrow.
Which of the following, if true, most helps to explain the surprising �nding?
(A) Tidal currents do not themselves dislodge barnacles from the shells of horseshoe crabs.
(B) Barnacles most readily attach themselves to horseshoe crabs in areas where tidal currents are weakest.
(C) The strength of the tidal currents in a given location varies widely over the course of a day.
(D) A very large barnacle population can signi�cantly decrease the ability of a horseshoe crab to � nd food.
(E) Until they are fully grown, horseshoe crabs shed their shells and grow new ones several times a year.
I have some questions about this one. First, can someone explain the meaning of choice A? Themselves refers to what? Also, about choice D, I am also a little confused the meaning it wants to transfer. Can someone explain it?
Thanks in advance!

The OA is E and I understand it is correct.

Crystal W wrote:In order to withstand tidal currents, juvenile horseshoe crabs frequently burrow in the sand. Such burrowing
discourages barnacles from clinging to their shells. When fully grown, however, the crabs can readily withstand
tidal currents without burrowing, and thus they acquire substantial populations of barnacles. Surprisingly, in
areas where tidal currents are very weak, juvenile horseshoe crabs are found not to have signi�cant barnacle
populations, even though they seldom burrow.
Which of the following, if true, most helps to explain the surprising �nding?
(A) Tidal currents do not themselves dislodge barnacles from the shells of horseshoe crabs.
(B) Barnacles most readily attach themselves to horseshoe crabs in areas where tidal currents are weakest.
(C) The strength of the tidal currents in a given location varies widely over the course of a day.
(D) A very large barnacle population can signi�cantly decrease the ability of a horseshoe crab to � nd food.
(E) Until they are fully grown, horseshoe crabs shed their shells and grow new ones several times a year.
I have some questions about this one. First, can someone explain the meaning of choice A? Themselves refers to what? Also, about choice D, I am also a little confused the meaning it wants to transfer. Can someone explain it?
Thanks in advance!

In option A, themselves refers to the tidal waves. The options means that the tidal waves do not dislodge the barnacles.
Option D is irrelevant to the discussion here.

Option E gives us a reason why there are less barnacles on the juvenile crabs.

Correct option: E