Answer:
C.
Explanation:
Let's identify some points here that are on the graph:
(0,0), (pi/2,-1), (pi,0).
Let's see if this is enough.
We want to see which equation holds for these points.
Let's try A.
(0,0)?
y=cos(x-pi/2)
0=cos(0-pi/2)
0=cos(-pi/2)
0=0 is true so (0,0) is on A.
(pi/2,-1)?
y=cos(x-pi/2)
-1=cos(pi/2-pi/2)
-1=cos(0)
-1=1 is false so (pi/2,-1) is not on A.
The answer is not A.
Let's try B.
(0,0)?
y=cos(x)
0=cos(0)
0=1 is false so (0,0) is not on B.
The answer is not B.
Let's try C.
(0,0)?
y=sin(-x)
0=sin(-0)
0=sin(0)
0=0 is true so (0,0) is on C.
(pi/2,-1)?
y=sin(-x)
-1=sin(-pi/2)
-1=-1 is true so (pi/2,-1) is on C.
(pi,0)?
y=sin(-x)
0=sin(-pi)
0=0 is true so (pi,0) is on C.
So far C is winning!
Let's try D.
(0,0)?
y=-cos(x)
0=-cos(0)
0=-(1)
0=-1 is not true so (0,0) is not on D.
So D is wrong.
Okay if you do look at the curve it does appear to be a reflection of the sine function.