Now that we have our facts laid out we can review the answer choices.
Gotsland does not need to triple its energy sources (just renewables).
Isn't relevant.
Gotsland doesn't need to decrease its use of non-renewables. It is mathematically possible for it to increase the total usage of total energy. In this scenario, non-renewables remains at 150 and renewables increases to 150 as well.
Yes, Gotsland MUST at least triple its use of non-renewables (to be at least 150 megawatts).
This may be the case, but there is nothing in the question to make this point.