Multiply the Radical Expressions $$( 6 - \sqrt { 13 } ) ( 6 + \sqrt { 13 } )$$

Multiple Choice

Multiply the radical expressions. $$( 6 - \sqrt { 13 } ) ( 6 + \sqrt { 13 } )$$

A) $- 133$
B) 23
C) 49
D) $36 - \sqrt { 13 }$