The product of any matrix by the scalar ......... Is the null matrix.

Explanation

To solve the question, we need to determine which scalar, when multiplied by any matrix, results in the null matrix (also known as the zero matrix).

### Step-by-Step Solution:

1. **Understanding the Null Matrix**:
The null matrix, denoted as \( O \), is a matrix where all elements are zero. For example, a \( 2 \times 2 \) null matrix looks like this:
\[
O = \begin{pmatrix} 0 & 0 \\ 0 & 0 \end{pmatrix}
...