To determine what quantity a half rest must be multiplied by to result in a whole rest, we can set up the equation as follows:
Let \( x \) be the quantity we need to find.
Since a whole rest is equal to 1 and a half rest is equal to \( \frac{1}{2} \), we have: \[ \frac{1}{2} \times x = 1 \]
To solve for \( x \), we can multiply both sides of the equation by 2: \[ x = 2 \]
Thus, a half rest must be multiplied by 2 to result in a whole rest.
The correct response is 2.