A woman in her first trimester of pregnancy is concerned about the effect that pregnancy will have on her appearance. She is fit but underweight, and she plans to restrict her weight gain as much as possible during pregnancy. How much weight do you advise her to gain?

a) 28 to 40 pounds
b) 15 to 25 pounds
c) 16 to 30 pounds
d) 25 to 30 pounds