residents of affected coastal cities continue to lobby for funds and request supplies to aid them in recovering from oil spills occurring more than a decade ago.

a. in recovering from oil spills occurring more than a decade ago
b. to recover from oil spills that had occurred more than a decade ago
c. in recovery of oil spills that occurred more than a decade ago
d. in recovering from oil spills having occurred more than a decade ago
e. in recovering from oil spills that occurred more than a decade ago

Here Idiom usage is AID IN.....

This eliminates option B.

Here the modifier Occured more than a century ago should modify the Oil spills as this is the one that occured.

So Option A is out.

C is wrong because of the usage Recovery , it's not recovery its recovering.

D is wrong because of the usage "having occured"

E is correct one that correctly places all the things.

Take Away is

a) Idiom usage
b) What is modifier modifying? is that the correct usage or not.