The Forward Difference Approximation Of $\frac { \partial u } { \partial t }$

Multiple Choice

The forward difference approximation of $\frac { \partial u } { \partial t }$ with step size k is

A) $( u ( x + k , t ) - u ( x , t ) ) / k$
B) $( u ( x - k , t ) - u ( x , t ) ) / k ^ { 2 }$
C) $( u ( x , t + k ) - u ( x , t ) ) / k$
D) $( u ( x , t - k ) - u ( x , t ) ) / k$
E) $( u ( x , t + k ) - u ( x , t ) ) / k ^ { 2 }$