The Result of the Trigonometric Identity (Sin X)( Sin Y)

Multiple Choice

The result of the trigonometric identity (sin x) ( sin y) is

A) 0.5 cos(x-y) - 0.5 cos(x+y)
B) cos(x-y) - cos(x+y)
C) -0.5 cos(x-y) + 0.5cos(x+y)
D) -0.5 cos(x-y) + cos(x+y)
E) none of the above