How is negative of an image obtained with intensity levels [0,L-1] with r and s being pixel values?

How is negative of an image obtained with intensity levels [0,L-1] wit

1.	How is negative of an image obtained with intensity levels [0,L-1] with r and s being pixel values?
A.	s = L 1 + r
B.	s = L 1 r
C.	s = L + 1 + r
D.	s = L + 1 + r
Answer» C. s = L + 1 + r