Given that, the rules for filling in the four symbols are as follows.
- Every row and every column must contain each of the four symbols.
- Every $2 \times 2$ square delineated by bold lines must contain each of the four symbols.
That means each row and each column in the grid must contain different symbols. In other words, no symbol can be repeated within the same row or the same column.
We have four symbols: $\bigcirc, \ast , \bigtriangleup$, and $\square$
We can easily fill it from the bottom.
Correct Answer: B