The correct option is D 7
The number in each circle represents the factor of the number given within the square/rectangle at the center.
Thus, to find the missing number, we need to find the factors of 14.
The factor pairs of 14 are:
1×14=14
2×7=14
7×2=14
14×1 = 14
Thus, the factors of 14 are 1, 2, 7, and 14.
Hence, the missing number is 7.