• Classification of Fatty Acids by Unsaturation:
• Saturated Fatty Acids (SFAs): No double bonds (e.g., Palmitic acid, $16:0$; Stearic acid, $18:0$).
• Monounsaturated Fatty Acids (MUFAs): Contain exactly one double bond in the acyl chain:

• Polyunsaturated Fatty Acids (PUFAs): Contain two or more double bonds:
• Linolenic acid ($18:3\text{n-3}$, 3 double bonds)
• Arachidonic acid ($20:4\text{n-6}$, 4 double bonds)
• nalysis:
• (Oleic acid): Correct monounsaturated fatty acid ($18:1\text{n-9}$).

Correct option: (3) Oleic acid