er_priyankajolly wrote:In 1988,average global temperature increased to highest recorded in 20th century, causing increased concern about the effects humans are having on global warming.

A) Same
B) to the level in 20th century that was highest recorded
C) to record high in 20th century
D) to a 20th century record high
E) to highest level recorded in 20th century.

OA E. Can anyone explain in the meanings of options C and D .. They are rejected due to change in meaning

I actually would have picked D here, if I had to choose an answer. You need a couple of definite articles in choice E: one to introduce "20th century," and one to introduce "highest level." To be correct, E would need to read "to the highest level recorded in the 20th century". Choice D at least uses an indefinite article, so it "sounds" less incorrect. I don't think any of these choices are particularly good, but A, B, C, and E are all missing definite and/or indefinite articles, and as a result, all seem as though they were written by someone who doesn't have a really thorough grasp of the English language. I don't know what the source was for this, but I don't think it's a very good example of a GMAT question. I wouldn't bother studying it if I were you.