Answer: c. $700
Step-by-step explanation:
Two key components of the GDP calculation are represented here.
Government Spending and Consumption.
In paying the soldier $500 the GDP has increased by $500 because this is Government Spending.
By then using $200 out of that money to to buy groceries produced in the USA she adds $200 to the GDP because that will then count as CONSUMPTION.
In total then $700 has been added to the GDP.