A Data Set Consists of 15 Pairs of Observations $\left( x _ { 1 } , y _ { 1 } \right) , \left( x _ { 2 } , y _ { 2 } \right) , \ldots \ldots \left( x _ { 15 } , y _ { 15 } \right)$

A data set consists of 15 pairs of observations $\left( x _ { 1 } , y _ { 1 } \right) , \left( x _ { 2 } , y _ { 2 } \right) , \ldots \ldots \left( x _ { 15 } , y _ { 15 } \right)$ If each $x _ { i }$ is replaced by $3 x _ { i }$ and if each $y _ { 1 }$ is replaced by $4 y _ { i } ,$ then the sample correlation coefficient r

A) increases by 3/15
B) increases by 4/15
C) remains unchanged
D) decreases by 3/15
E) decreases by 4/15