Correct Answer: C
Explanation:
During the period from Tuesday through Friday, it is possible that Xavier works twice as many days (2) as Yussef (1). It is not possible for all four greenskeepers to work together on a given day, since on the day before/after, none of them could work. Nor is it possible for any greenskepers to work three times as many days as another, since this would mean working three out of the four days (Tuesday – Friday) which would require working two consecutive days.