Sentence Correction

Many of these gene flaws - there are plenty of them, with names like BCR-ABL - are relative newcomers to medical terminology, as are a majority of the new anti-tumor drugs, still in early testing, that are aimed at them.

A medical terminology, as are a majority of the new anti-tumor drugs, still in early testing, that are aimed at them.
B medical terminology like a majority of the new anti-tumor drugs that are still in early testing, and aimed at them.
C medical terminology, as are a majority of the new anti-tumor drugs that are still in early testing, aimed at them.
D medical terminology like a majority of the new anti-tumor drugs, still in early testing, that are aimed at them.
E medical terminology, as are a majority of the new anti-tumor drugs, still in early testing, and aimed at them.

My answer is C .

A and D are wrong 'that....' does not work on GMAT.
B and E can be eliminated because the last part looks bizarre 'and aimed at them'

C is correct because aimed at them ..what is aimed testing which it is modifying .