Explanation
"Wastrel" refers to a person who wastes money or resources, making "Spendthrift" its synonym, not an antonym. Since the question asks for the meaning of "Wastrel," the correct choice is "Spendthrift," as both describe someone who spends recklessly. The other options—"Sophisticate" (refined person) and "Modicum" (small amount)—do not match this meaning.