IMO C. D is not parallel

saurabhmahajan wrote:The Senate approved immigration legislation that would grant permanent residency to millions of aliens currently residing here and if employers hired illegal aliens they would be penalized.

A) if employers hired illegal aliens they would be
penalized

B )hiring illegal aliens would be a penalty for
employers

C )penalize employers who hire illegal aliens

D )penalizing employers hiring illegal aliens

E) employers to be penalized for hiring illegal
aliens


Why not D ?

IMO: C

Only option C helps in maintaining the parallel structure of the sentence.. ABC approved something that would X and Y...

The Senate approved immigration legislation that would grant permanent residency to millions of aliens currently residing here and penalize employers who hire illegal aliens

I understand how we arrived at answer choice C since the rest of the answers do not fit. However i have a doubt as below

As per Manhattan SC guide when two clauses are in parallel we need to repeat the same word as in

A mastodon carcass,which has been thawed only once AND which is still fresh is on the display. (Note: Here we repeat the which)

In the same way we had to repeat 'that' in sentence that is posted. Even though this option is not given in the answer choice i wanted to understand in what way its an exception to the rule that we need to repeat the words when relative clauses are parallel.