Sentence correction

[cherijose]

<The old geezer aggravated his younger counterparts by consistently producing more work than them.>

A) The old geezer aggravated his younger counterparts by consistently producing more work than them.

B) The old geezer aggravated the younger counterparts by consistently producing more work than they.

C) The old geezer irritated the younger workers by consistently producing more work than them.

D) The old man irritated his younger workers by consistently producing more work than them.

E) The old man irritated his younger workers by consistently producing more work than they.

OA is E. Please help me understand if they/ them is subject or object.

[tim]

i don't buy that this is a GMAT Prep question. please post a screen shot..