The answer is A: comes one-half to two-thirds up the side of the food.
Explanation for each option:
A. Comes one-half to two-thirds up the side of the food - This is the correct answer. When pan frying, the oil should be deep enough to cook the food evenly and create a crispy exterior, which typically means the oil should reach about halfway to two-thirds up the side of the food.
B. Covers the food entirely - This describes deep frying, not pan frying. In deep frying, the food is completely submerged in oil.
C. Comes within an inch of the top of the pan - This is not ideal for pan frying as it suggests using too much oil, which can be unsafe and lead to splattering.
D. Lightly coats the bottom of the pan - This is more appropriate for sautéing, where only a small amount of oil is used to cook food quickly over high heat.
In summary, for pan frying, the oil should come one-half to two-thirds up the side of the food to ensure proper cooking and texture.