31. Which value is not possible?

$$\begin{array}{lcl} In\;the\;expression\;3a-4b=16,\;a\;and\;b\\ are\;integers.\;Which\;of\;the\;values\;for\;b\\ below\;is\;NOT\;possible?\\ \\ (A)\; -4\\ (B)\; -1\\ (C)\; 2\\ (D)\; 3\\ (E)\; 5\\ \end{array}$$