If Joe is making an effort to lose weight, it would be in his best interest to make healthy choices when going out to dine. Therefore, making a (C) gluttonous, “tending to eat and drink excessively,” or a (B) detrimental, “causing harm or injury,” choice for dinner would be the opposite of what he should be doing. He may choose an (D) acerbic, “bitter” or “sharp in taste,” dish for dinner, but there’s no telling if that would be a healthy or unhealthy choice. Because the adjective in question applies to food, choice (E) loquacious makes no sense since it means “talkative.” This leaves choices (A) abstemious, “moderate in appetite,” and (F) austere, “stern” or “strict,” which make sense when describing a selection that someone on a diet would make.