What measure of center should Mr malloy use for Amo and for Javier for the best possible grade

The answer to this question is the first item in the choices which is "The teacher should use the mean for both Amo and Javier" when computing and comparing their grades. The mean is the average grade while the median is the center of the grade. It would be wrong to apply median in computing their grades and it would be also wrong when the use two different methods when computing and comparing their grades.