A fatty acid is made of a polar carboxylic acid functional group and .

a polar hydrocarbon tail

a nonpolar hydrocarbon tail

a polar ring containing an amino group

A nonpolar ring containing an amino group

A fatty acid is made of a polar carboxylic acid functional group and a nonpolar hydrocarbon tail.

Explanation:

A fatty acid is made of fat-soluble components, that consists of a large (more than 4 carbon atoms) aliphatic chain of carbon atoms, with hydrogen atoms and a carboxyl group (-COOH). The named fatty acid is because of the -COOH group.

The chain can be made of carbon atoms with a single bond, (saturated) or with double or triple bonds (unsaturated). When the fatty acid has just one double bond the fatty acid is monounsaturated, and otherwise, if it has multiple double bonds it is polyunsaturated. Fatty acid chains can be different in their lengths and their degree of unsaturation.          

Mostly of the tail of the fatty acid is nonpolar and hence, hydrophobic, because the long-chain made of hydrocarbon atoms.

From all of the above, the correct answer is option b: A fatty acid is made of a polar carboxylic acid functional group and a nonpolar hydrocarbon tail.

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