At large -x values the -3^x nears zero and the expression is equal to ~4

as x approaches 0 the -3^x becomes -1 and the expression becomes 3

as x goes positive -3^x becomes a large negative number dwarfing the '4' in the expression and the entire expression becomes more and more negative

So it has a maximum of ALMOST 4 and is less than that or negative everywhere else......

Answer "B"