The males of the species are more interested than the females in colle

IMO (C) should be correct.

C. in collecting food than the females, spend the majority of their time in the deep waters and search

The male species are interested in what? The answer to that is food

Compared to whom? The females.

And as a result what to do that? Spend time in deep waters looking for small fish

Other options do let us understand the intention of the author, however, (C) fits best to give the answer in a systematic manner and along with the correct tense.

(A). I took 01:37. A brilliant question indeed. Nice use of parallelism, intended meaning, and comma + verb-ing modifier.

Analysis: From the initial read we can make out the meaning- Males are more interested in collecting food than are females. What follows next depicts, "how they are more interested" or "what actions" of theirs prove their more interest. So, the comma + spending the majority of their time in the deep waters searching for small fish and other edibles, modifies the preceding verb/action. And, the original statement looks pretty much thorough with this meaning with properly placed modifiers and grammar.
Correct for the reasons stated above. One more thing to note here is- "You have to see the use of "ellipsis" by the author after than the females". Complete sentence without ellipsis will be: The males of the species are more interested in collecting food(optional but redundant) than the females are interested(optional but redundant) in collecting food. As, "are interested" is stated ahead in the sentence, it is okay to not repeat that part again after "than the females". And as mentioned above in analysis, comma + spending modifies the entire preceding clause (action modifier if you like the jargon).

This makes in collecting food, in spending time, and in searching fish three separate entities. This is not the correct sequence. The latter two modify the first action. So, this option choice, though grammatical, distorts the intended meaning and is thus wrong.

You can interpret two meanings from this sentence:
The males are more interested in collecting food than females are interested in collecting food, or,
The males are more interested in collecting food than in collecting the females. (Dothrakis?)
Some may argue that the latter may not make much sense, and that is true, but it does lead to an meaning ambiguity which (A) avoids completely by not placing in collecting and the females on two sides of comparison marker "than". So, (A) is better than (D). Also, the part after comma + spend is problematic. The grammar is off. There's no reason to use Simple Past tense when the first part is stated nicely in Present tense. Such verb tense change is not appreciated in GMAT. Also, if the verb change has to happen, it should be done organically and with proper conjunction.

Same meaning error as choice (C).

This corrects the meaning error in (C) and (D) by placing "are" in front of "the females". But, it introduces pronoun ambiguity with "who" referring to the females. Now, the action of spending majority time and searching for fish in deep waters is attributed to the females and not the males. This is not the meaning that is intended by the author. Hence, this is also incorrect.

GMAT Club Tests Official Explanation:

A. CORRECT. Comparison between “the males” and “the females” is correctly established. Use of present participle “spending” makes it clear in what way the males are more interested in collecting food. Use of present participle “searching” correctly establishes its bearing on “spending” - this construction makes it clear how the males spend time in deep waters.

B. The three items “ in collecting”, “ in spending” and “ in searching” are wrongly made parallel. This construction indicates that the males are interested in all these three items parallelly and the bearings between these items are lost.

C. Comparison is ambiguous: It is not clear what is meant, whether
a. the males are more interested in collecting food than in females
or whether
b. the males are more interested in collecting food than the females are

The three verbs “are interested”, “spend” and “search”.are wrongly made parallel. This construction indicates that the males execute these three activities parallelly and the bearings between these items are lost.

D. Comparison is ambiguous: It is not clear what is meant, whether
a. the males are more interested in collecting food than in females
or whether
b. the males are more interested in collecting food than the females are.

The two present participles “spending” and “searching” are wrongly made parallel. This construction does not make it clear how the males spend time in deep water, i.e. it is not clear that the males spend time in deep waters searching for food - the bearing between “spending” and “searching” is thereby lost.

E. The relative clause “who spend…” wrongly refers to “the females”, conveying the wrong meaning. The intended meaning is that the males spend time.