What is the relation between the entry and exit entropy of an actual supersonic diffuser?

What is the relation between the entry and exit entropy of an actual

1.	What is the relation between the entry and exit entropy of an actual supersonic diffuser?
A.	s1 = s2
B.	s1 > s2
C.	s1 < s2
D.	s1 s2 = 1
Answer» D. s1 s2 = 1