Answer:
Of the given attachments, the first attachment is the correct answer.
Step-by-step explanation:
A fatty acid refers to a lengthened hydrocarbon chain, which comprises a carboxylic group. The two main kinds of fatty acids are unsaturated and saturated fatty acids. An unsaturated fatty acid comprises a double bond within the fatty acid chain. In case, if a fatty acid comprises more than one double bond than it is termed as polyunsaturated fatty acid.
Thus, of the given attachments, the first attachment comprises the carboxylic acid with a lengthened hydrocarbon chain and double bond in its composition.