Find the Indicated Function and Write Its Domain in Interval $$s ( x ) = \frac { x - 5 } { x ^ { 2 } - 49 } , t ( x ) = \frac { x - 7 } { 5 - x } , ( s \cdot t ) ( x ) = ?$$

Multiple Choice

Find the indicated function and write its domain in interval notation.
- $$s ( x ) = \frac { x - 5 } { x ^ { 2 } - 49 } , t ( x ) = \frac { x - 7 } { 5 - x } , ( s \cdot t ) ( x ) = ?$$

A) $- \frac { 1 } { x + 7 } ; ( - \infty , - 7 ) \cup ( 7 , \infty )$
B) $\frac { 1 } { 7 - x } ; ( - \infty , - 7 ) \cup ( - 7,5 ) \cup ( 5,7 ) \cup ( 7 , \infty )$
C) $\frac { 1 } { 7 - x } ; ( - \infty , 7 ) \cup ( 7 , \infty )$
D) $- \frac { 1 } { x + 7 } ; ( - \infty , - 7 ) \cup ( - 7,5 ) \cup ( 5,7 ) \cup ( 7 , \infty )$