William is three years of age. Six months ago, William's mother decided that her son was too fat, so she began feeding him a low-fat diet that only contained apples, peaches, orange juice, leafy greens, and fat-free milk and cottage cheese. She doesn't like red meat, vegetable oils, eggs, fish or turkey, so she also doesn't feed these foods to her son. Recently, she noticed William's skin was scaly and not smooth, and some of his hair had fallen out. He had lost weight, but he wasn't growing taller. Based on this information, William probably has____
a) Cardiovascular disease
b) Chronic hypertension
c) Ketosis
d) Essential fatty acid deficiency