4. (10 points) In a $6 \times 6$ grid, place a Go stone in each cell, with 1 stone per cell, such that the number of white stones in each row is different, and the number of white stones in each column is the same. How many black Go stones are there in this $6 \times 6$ grid?
A. 18
B. 14
C. 12
D. 10
【Analysis】According to the problem, the number of items in each row can be $0, 1, 2, 3, 4, 5, 6$, and since each column is equal, the total must be a multiple of 6. Then, from these 7 numbers, remove one number so that the sum of the remaining 6 numbers is a multiple of 6, which can solve the problem (the remaining positions are filled with black Go stones).

【Solution】Solution: The number of items in each row can be $0 \sim 6$,
Each column is equal, so it must be a multiple of 6,
$$
0+1+2+3+4+5+6=21 \text {, }
$$

If 3 is removed, then the remaining numbers: $21-3=18$ is exactly a multiple of 6,
So, there are 18 white stones,
Then, the number of black Go stones is: $6 \times 6-18=18$ (stones)
Therefore, the answer is: A.