Let $a, b, c$ be positive integers with $a^2 + b^2 = c^2$. Which of the following must be true? (A) 3 divides exactly one of $a, b$ (B) 3 divides $c$ (C) $3^3$ divides $abc$ (D) $3^4$ divides $abc$
(D) $3^4$ divides $abc$.
Let $a, b, c$ be positive integers with $a^2 + b^2 = c^2$. Which of the following must be true?
(A) 3 divides exactly one of $a, b$ \quad (B) 3 divides $c$ \quad (C) $3^3$ divides $abc$ \quad (D) $3^4$ divides $abc$