Advertisement: Researchers studied a group of people trying to lose weight and discovered that those in the group who lost the most weight got more calories from protein than from carbohydrates and ate their biggest meal early in the day. So anyone who follows our diet, which provides more calories from protein than from anything else and which requires that breakfast be the biggest meal of the day, is sure to lose weight.

Question: The reasoning in the advertisement is most vulnerable to criticism on the grounds that the advertisement overlooks the possibility that
Options:
A. eating foods that derive a majority of their calories from carbohydrates tends to make one feel fuller than does eating foods that derive a majority of their calories from protein.
B. a few of the people in the group studied who lost significant amounts of weight got nearly all of their calories from carbohydrates and ate their biggest meal at night.
C. the people in the group studied who increased their activity levels lost more weight, on average, than those who did not, regardless of whether they got more calories from protein or from carbohydrates.
D. some people in the group studied lost no weight yet got more calories from protein than from carbohydrates and ate their biggest meal early in the day.
E. people who eat their biggest meal at night tend to snack more during the day and so tend to take in more total calories than do people who eat their biggest meal earlier in the day.
Answer: "C"