Why is the correct answer A?

Sorry, I meant why is it not* A.

@cjahangiri, (A) is incorrect because this conclusion is unwarranted. The stimulus tells us that winds have cooling effect and thus may allow for higher electric load on the transmission line without exceeding its maximum operating temperature. But the fact that the utility company has an option to increase the load on days when the winds are stronger cannot lead us to conclude that the utility would typically do so as (A) appears to suggest as the reasons utility chooses to increase/ reduce load on the transmission lines are independent of the temperature, rather the temperature merely serves as a limiting factor. Let me know if you have any further questions.