Express as the Logarithm of a Single Expression $\log _ { b } x + \log _ { b } y$

Multiple Choice

Express as the logarithm of a single expression. Assume that variables represent positive numbers.
- $\log _ { b } x + \log _ { b } y$

A) $\log _ { 2 b } ( x + y )$
B) $\log _ { 2 b } x y$
C) $\log _ { b } ( x + y )$
D) $\log _ { b } x y$