Factor Out the Largest Possible Common Factor $5 a ( a - b ) + ( a - b )$

Multiple Choice

Factor out the largest possible common factor.
- $5 a ( a - b ) + ( a - b )$

A) $\left( 5 a ^ { 2 } + 5 b \right) + ( a - b )$
B) $5 a ( a - b )$
C) $6 a ( a - b )$
D) $( a - b ) ( 5 a + 1 )$