Sentence Correction

In a state of pure commercial competition, there would be a large number of producing firms, all unfettered by governmental regulations, all seeking to meet consumer needs and wants more successfully than each other.

A)all seeking to meet consumer needs and wants more successfully than each other.
B)all seeking more successfully to meet consumer needs and wants than the others.
C)each seeking to meet consumer needs and wants more successfully than one another.
D)each seeking to meet consumer needs and wants more successfully than the others.
E)each seeking successfully to meet consumer needs and wants than another

Please, your help and confirmation whether my reasoning in eliminating the choices is correct:
a) "each other" doesn't make sense in the sentence. In this case, we cannot compare "all" with "each other". The objective is to compare the individual effort of each one with the rest of the producing firms.
b) Misplaced modifier: Now "more succesfully" modifies "all seeking". It changes the intended meaning. "Others" doesn't make sense for the similar reasons in A.
c) "one another" is wrong. The idea of reciprocity is not required in this sentence.
d) Correct.
e) Misplaced modifier.

I have two additional doubts:
a) Is the structure in the choice an absolute phrase (a noun with a noun modifier that modifies the entire clause)? If the choices were noun modifiers, they would be modifying "government regulations" because noun modifiers modify the nouns next to them.
b) Is there a problem with "all"? In other words, could be there a structure correct using "all"?

Thanks!

OA is D .