All of the Following Are Solutions to the Wave Equation $y ( x , t ) = A \cos [ k ( x - v t ) ]$

Multiple Choice

All of the following are solutions to the wave equation except for

A) $y ( x , t ) = A \cos [ k ( x - v t ) ]$
B) $y ( x , t ) = A \cos ( k x - a t )$
C) $y ( x , t ) = A \cos [ 2 \pi ( x / \lambda - f ) ]$
D) all of the first three are correct.
E) none of the first three is correct.