BMI is a decent measure of ideal weight; however, it is errorprone too. The most important aspect is that it does not differentiate between lean tissue and body fat. For example, an athlete needs much more muscle mass than the average person and thus he could be by the standards of the BMI close to obesity, while in reality he is very healthy. The contrary could also happen; one could have a very bad diet and be skinny but with more fat than he should have. Correct answer is C.