If applying 10 gallons of herbicide per acre on a 20-acre field, how many gallons of herbicide are needed?

To determine the total amount of herbicide needed for a 20-acre field when applying 10 gallons per acre, you multiply the rate of application by the total acreage. The calculation is straightforward:

10 gallons/acre × 20 acres = 200 gallons.

Thus, for this application scenario, you would need a total of 200 gallons of herbicide to cover the entire field.

Given this context, the correct response indicates that applying 10 gallons per acre results in a total of 200 gallons for 20 acres. The answer provided does not reflect this calculation accurately and is therefore not the appropriate choice.