The correct option is A 7
Prime factorization of 7623:
37623325411184711777
∴7623=3×3––––––×11×11––––––––×7
=32×112×7
Here, 7 is not paired.
So, 7623 when divided by 7 gives 32×112 which is a perfect square.
Therefore, the smallest number by which 7623 must be divided to get a perfect square is 7.