Answer;
The first choice (A) is an unsaturated fatty acid.
Explanation;
-An unsaturated fat is a fat or fatty acid in which there is one or more double bond in the fatty acid chain.
-A fat molecule is monounsaturated if it contains one double bond, and polyunsaturated if it contains more than one double bond. In this case, the unsaturated fat (A) is polyunsaturated.
Well, the food is in the environment. I would like to compare it with how bacteriae feed (however my biology is quite rusty), that is, they engulf their food and they "digest" -- not the proper term, since there are no organs to do real digestion -- it.