The correct answer is C. Hopeful.
Synonyms are words that have the same or nearly the same meaning as another word. In this case, the word “sanguine” means “having or showing a cheerful and confident mood.” The other options, “clever,” “proud,” and “modest,” do not have the same meaning as “sanguine.”
Clever means “having or showing a quick wit and intelligence.” Proud means “having or showing an excessively high opinion of oneself.” Modest means “having or showing a moderate or humble estimate of one’s own importance.”
Hopeful means “having or showing expectation of a good outcome.” This is the closest synonym to “sanguine” because it also refers to a positive attitude.