细节理解题。根据文章倒数第二段最后一句“Those who were breast-fed for 12 months or more had IQ test scores that were 3.76 points higher than those who were breast-fed for less than one month, the team found.”可以 知道，通过母乳喂养长大的孩子可以获得更高的IQ测试分数，也即更聪明，这与选项C一致。根据最后一段最后一句话“Those who were breast-fed stayed longer in school for about an extra year and had monthly salaries that were about a third higher.”可以知道通过母乳喂养长大的孩子上学的时间更长，月薪高出约1/3。这与A项和D项一致。只有B项未提及，因此选择B选项。