If you care about who is factually correct, then it’s person 2 and 4:

Palmitic acid (hexadecanoic acid in IUPAC nomenclature) is a fatty acid with a 16-carbon chain. It is the most common saturated fatty acid found in animals, plants and microorganisms.

(Although person 3 is correct in that it is a carboxylic acid. It doesn’t exclude the other terms though.)