To find out how many finches the population grew by each year, you can divide the total increase in the population by the number of years.
The total increase is 75 finches over a period of 3 years.
Calculation: \[ \text{Increase per year} = \frac{\text{Total increase}}{\text{Number of years}} = \frac{75 \text{ finches}}{3 \text{ years}} = 25 \text{ finches/year} \]
So, the population grew by 25 finches each year.
The correct response is: 25 finches.