Esther Would Like to Gain Weight,but Despite Eating Regular Meals

Esther would like to gain weight,but despite eating regular meals and having no disordered eating practice or eating disorder,her BMI dropped from 19.0 to 16.2 in one year.According to this information,Esther's physician will need to

A) let Esther know that she shouldn't try to gain weight,because her BMI is in the healthy range.
B) provide Esther with a low-fat,low-carb diet that provides 900 kcal/day to gain weight.
C) treat Esther with hypermetabolic medications.
D) determine whether Esther has cancer or another chronic disease.