$A$ point $P$ is moving in uniform circular motion with radius $3 \ m$. Let at some instant the acceleration of the point be $a = (6 \hat{i} - 4 \hat{j}) \ m/s^2$,the position vector be $r$,and the velocity vector be $v$. Choose the correct statement.

• A
  $v \cdot a = 0$ and $r \times a \neq 0$
• B
  $v \cdot a \neq 0$ and $r \times a \neq 0$
• C
  $v \cdot a = 0$ and $r \times a = 0$
• D
  $v \cdot a \neq 0$ and $r \times a = 0$