To find the change in the amount of water in gallons per minute, we first determine the rate at which the pump removes water.
The pump removes 250 gallons in 5 minutes. To find the rate per minute, we can divide the total amount of water removed by the time:
\[ \text{Change in water per minute} = \frac{250 \text{ gallons}}{5 \text{ minutes}} = 50 \text{ gallons per minute} \]
Since the water is being removed from the tank, this is a negative change. Therefore, the change in the amount of water in 1 minute is:
\[ -50 \text{ gallons} \]
Thus, the correct response is:
\(-50\) (negative 50)