Find the Slope of the Line Determined by This Pair $( a , 0 ) , ( 0 , b )$

Multiple Choice

Find the slope of the line determined by this pair of points. $( a , 0 ) , ( 0 , b )$

A) $- \frac { b } { a }$
B) $\frac { a } { b }$
C) $- \frac { a } { b }$
D) $\frac { b } { a }$
E) undefined