2016/17 AHSMC Part 1 Problem 7

Let $A \le B \le C$ be the measures in degrees of the angles of $\triangle ABC$. Since $A+B+C = 180^\circ$ one of the angles should be even and hence $A = 2^\circ$. On the other hand, $178^\circ = B+C \le 2C$, hence $C \ge 89^\circ$. Since $89$ is prime, we can take $B = C = 89^\circ$, $A = 2^\circ$. The answer is (D).