Joe claims that the equation y = 2x + b, where b is a real number, represents the graph of a straight line. 
 Which statement best classifies Joe's claim?
 A.Joe's claim is true only when b is 0.
 B.Joe's claim is true for all values of b.
 C.Joe's claim is not true for any value of b.
 D.Joe's claim is true only when b is not zero.