Complete the Property of Exponents $b ^ { n } \cdot b ^ { m } =$

Multiple Choice

Complete the property of exponents. $b ^ { n } \cdot b ^ { m } =$ _____

A) $b ^ { n } + b ^ { m }$
B) $b ^ { n + m }$
C) $b ^ { n - m }$
D) $b ^ { n \cdot m }$