Help me analyse the structure of the sentence again :'(

I totally got stuck this time.

The question goes like this:

All eels spawn in the sea, the eggs hatching into transparent, ribbon-like larvae -----, feeding until they metamorphose into small eels.
A, that drift about
B, drift about
C, about drifting
D, drift about them

I'd admit the whole sentence is a lil too complicated. It took me a long time to analyze it. But I still cannot get it done.

Okey, lemme first give it a shot, then you tell me whether I get it right or wrong.

First of all, leave out those errr... unimportant or modifying words, then we get,

All eels spawn the eggs (which are) hatching into larvae -----, feeding until they metamorphose into small eels.

Then we need a clause to modify 'larvae', right? So the answer is no doubt A. But, my question came out now,

Why they use 'feeding' here, instead of 'feed' or 'are fed'? Let's look at this,
'the eggs are hatching into larvae that drift about, feeding until they metamorphose into small eels.'

Does it sound ridiculous?

Sorry, Mr Pedantic. I just edited my post. You know, I was kinda losing my mind. The answer is A, but I said 'so the answer is no doubt C'.

So why do you think A is correct? Can you explain for me why 'feeding' is used here, instead of 'feed', 'are feeding', 'are fed' or whatever?

So 'feeding' here used as a participle modifies eggs not larvae? It makes sense. But why not add 'and' before it?

Another question here about 'hatch',

We say 'eggs hatched', but we can't say 'eggs were hatched', right?

I guess I get it now. I'm just not used to this kinda situation: we already had an attributive clause to modify a noun, but another participle tried to get in and modified it together. hehe

Yeah, they are eely and creepy. I hafta say I hate doing this stuff.

What really gets me is what stuff we don't need to put 'the' in front of, or what abstract nouns we can use as plural form.