Answer: Option d.
Step-by-step explanation:
We know that City A has a steady wind speed of 10 knots and City B has a variable speed between 8 and 12 knots roughly the same proportion of time.
From this, we know that the average wind speed in city B is equal to the mid value in that interval.
We can calculate the mid value as the sum between the lower extreme and difference between the extremes divided by 2.
M = 8 + (12- 8)/2 = 8 + 2 = 10
So the average wind speed in city B is 10 knots.
From this we can conclude that both cities produce the same amount of power.