Question says maximum t courses a student can register, Let us assume that there are 5 courses at max. so take t=5 ,
maximum p students can take each course , so let p = 2
for student table L is number of tuple so L = 5 ( as it is said at least one student per course ) and for courses table Z is number of tuples , so Z = 5 ( calculated from this line - Each student is enrolled to at least one course and each course has at least one student. )
now option A and D are true.
option A must be TRUE if we assume there is at least one student .
option D says L <= 10 so take L=5 which is < 10 so condition is True.
For option B ,
Z <= t * L put t =5 and Z = 5 and L = 5 it becomes 5<= 25 that is TRUE.
For option C ,
L >= p × Z put L,p,Z value it becomes 5 >= 2 * 5 means 5 >= 10 that is False .
Hence option C need not be correct.