Final answer:
The essential fatty acids that must be obtained from the diet are linoleic (A) acid and alpha-linolenic (D) acid because the human body cannot synthesize them.
Step-by-step explanation:
Which essential fatty acids must be obtained from food because the body cannot make any or enough? The essential fatty acids that must be obtained from food are linoleic acid (an omega-6 fatty acid) and alpha-linolenic acid (an omega-3 fatty acid), as humans cannot synthesize them. These include options (a) and (d) from the list provided. Specifically, they are necessary for good health, normal growth, and development.
The body can synthesize arachidonic acid from linoleic acid, so it is not an essential fatty acid that must be obtained from the diet. Palmitic acid and omega-3 fatty acids, like eicosapentaenoic acid and docosahexaenoic acid, can actually be synthesized in the body from alpha-linolenic acid, although it is more efficient to consume them directly through the diet.
So, the answer is A and D.