A Student Reports That, of a Simple Random Sample of 50

Multiple Choice

A student reports that, of a simple random sample of 50 college undergraduate students, 21% were taking more than fifteen credit hours. We know that the student has made a mistake (or maybe really did not conduct the survey) . Why?

A) There are 50 students in the sample, so percentages should be multiples of 2%.
B) There are 50 students in the sample, so percentages should be multiples of 0.02%.
C) 21% of 50 students is 10.5 students, and you cannot sample a fraction of a student.
D) Both A and C are correct.
E) Both B and C are correct.