Answer : 3. "Insult"
Explanation :

The most appropriate synonym for "affront" is "insult." An affront is a deliberate act or display of disrespect, and insult reflects a similar idea of offensive behavior or language. The other options, such as "depress" (make someone feel low or sad), "fail" (not succeed), and "tolerate" (put up with), have different meanings and do not capture the sense of offense implied by "affront."