Simplify the Following Algebraic Expression and Express Your Answer Using $u ^ { - 7 } u ^ { - 6 }$

Multiple Choice

Simplify the following algebraic expression and express your answer using positive exponents only. $u ^ { - 7 } u ^ { - 6 }$

A) $u ^ { 13 }$
B) $\frac { 1 } { u ^ { 13 } }$
C) $\frac { 1 } { u ^ { 42 } }$