Answer:
A) Population A has a high water potential and loss due to transpiration because of the increased humidity.
Explanation:
Notice that the hypothesis is that relative humidity affects the transpiration of the body. So, in order to prove such hypothesis, we need to find enough evidence about water loss due to higher humidity. Knowing the relative humidity as the relation between water vapor and the pressure of it.
Therefore, the right answer is A, because we need to prove that a high water potential and loss due to transpitation happens because of the increased humidity.