Calculate the Slope of the Straight Line Through the Points $( 2,1 )$

Multiple Choice

Calculate the slope of the straight line through the points $( 2,1 )$ and $( 5,10 )$ . Try to do the calculations mentally.

A) $m = 9$
B) $m = - 3$
C) $m = \frac { 1 } { 3 }$
D) $m = - \frac { 1 } { 3 }$
E) $m = 3$