After decreasing steadily in the mid-1990's, the percentage of students in the United States finishing high school or having earned equivalency diplomas increased in the last three years of the decade, up to 86.5 percent in 2000 from 85.9 percent in 1999 and 84.8 percent in 1998.
(A) finishing high school or having earned equivalency diplomas increased in the last three years of the decade, up to 86.5 percent in 2000 from 85.9 percent in 1999 and
(B) finishing high school or earning equivalency diplomas, increasing in the last three years of the decade, rising to 86.5 percent in 2000 from 85.9 percent in 1999 and from
(C) having finished high school or earning an equivalency diploma increased in the last three years of the decade, and rose to 86.5 percent in 2000 from 85.9 percent in 1999 and from
(D) who either finished high school or they earned an equivalency diploma, increasing in the last three years of the decade, rose to 86.5 percent in 2000 from 85.9 percent in 1999 and
(E) who finished high school or earned equivalency diplomas increased in the last three years of the decade, to 86.5 percent in 2000 from 85.9 percent in 1999 and
The issues:
Noun + Present participle:
NOUN + Present participle--> NOUN + Verbing
In this case the Verbing modifies the NOUN adjacent to it.
Example:
The man working in a saw mill has risk of accident.
--> Working modifies the man.
So, in the "United States + finishing/having", Verbing modifies USA.
==> Then the meaning becomes "USA is finishing/having high school". It changes the meaning of the sentence.
This kills the options A, B, and C.
2. NO Comma + Who:
Noun + Preposition + Noun + Who
--> In this situation who will refer to the eligible noun. Eligible noun will meet the following two conditions:
2.1. It agrees with the verb after who.
2.2. It makes the sentence meaningful.
2.3. Who cannot refer to things. Who refers to person(s).
Example:
The students in high school who have scored high will be awarded.
--> So, in D and E, who refers to the percentage of students
3. Either X or Y:
--> X and Y MUST be parallel.
In the option D, "either finished high school or they earned" does not maintain the parallelism.
It should be either finished or earned
--> This kills D.
Answer is E.