Fill in the Blank Using the Word Product, Sum, Quotient $\sin \alpha \cos \beta = \frac { 1 } { 2 } [ \sin ( \alpha + \beta ) + \sin ( \alpha - \beta ) ]$

Multiple Choice

Fill in the blank using the word product, sum, quotient, or difference.
-The formula $\sin \alpha \cos \beta = \frac { 1 } { 2 } [ \sin ( \alpha + \beta ) + \sin ( \alpha - \beta ) ]$ can be used to change aــــــــــــــ of a sine and a cosine into the ــــــــــ of two sine expressions.

A) product, sum
B) product, difference
C) quotient, sum
D) quotient, difference