Critical Reasoning

The ice on the front windshield of the car had formed when moisture condensed during the night. The ice melted quickly after the car was warmed up the next morning because the defrosting vent, which blows on the front windshield, was turned on full force.

Which of the following, if true, most seriously jeopardizes the validity of the explanation for the speed with which the ice melted?

A. The side windows had no ice condensation on them

B. Even though no attempt was made to defrost the back window, the ice there melted at the same rate as did the ice on the front windshield.

C. The speed at which ice on a window melts increases as the temperature of the air blown on the window increases.

D. The warm air from the defrosting vent for the front windshield cools rapidly as it dissipates throughout the rest of the car.

E. The defrosting vent operates efficiently even when the heater, which blows warm air toward the feet or faces of the driver and passengers, is on.

is it D

is it B?

IMO: B

Question:
Which of the following, if true, most seriously jeopardizes the validity of the explanation for the speed with which the ice melted?

I believe most seriously jeopardizes is synonymous with weakens.

With that in mind;

(A) irrelevant

(B) best answer IMO. It weakens the theory by saying the ice on the back window melted at the same rate as the ice on the front window even though no attempt was made to defrost the back window

(C) strengthens the argument, the opposite of what we are trying to do

(D) irrelevant

(E) irrelevant

B is the best answer.

D in a way supports the argument.

imo B

imo B

OA (B)

Why is D wrong?It mentions that air cools as it spreads around the car which seconds the condensation of the moisture to ice.B talks about the back window which is not mentioned in the argument at all.

to answer your question, @singalong -

D --> The warm air from the defrosting vent for the front windshield cools rapidly as it dissipates throughout the rest of the car.

premise --> The ice melted quickly after the car was warmed up the next morning because the defrosting vent, which blows on the front windshield, was turned on full force.

We are concerned about the windshield here. The choice D clearly says that the warm air rapidly cools as it moves to the rest of the car. So, in all probabilities, the warm air stays warm in and around the windshield - this does not weaken the conclusion.

But B points the cause of the melting to another direction and implies that some other cause was responsible. even though no defrosting attempt was made in the rear side, the ice did melt at the same rate. That clearly nullifies the effect of the defrost vent and renders the conclusion powerless.

Hope that helps!

we have a causal relation in the statements.
X -> Y
X = the defrosting vent blowing only on the front windshield. turned on full force.
Y = ice melt quickly on the windshield

D says. warm air cools rapidly and dissipates through the rest of the car. So since it is focused on Front Windshield, it has a positive impact on it as compared to anyother windshields (say). So in a way, this actually strengthens the arg indirectly.

B says. If back windshield also melts at the same rate, then X is actually not the reason.
Hence it jeopardizes the argument.

Ans: B