For which of the following functions is f(w+b)=f(w)+f(b) for all positive numbers w and b? Choose the correct choice from the following answers:
A) a) f(x)=x^2
B) b) f(x)=x+1
C) c) f(x)=root x
D) d) f(x)=2/x
E) e) f(x)= -3x
f(w+b)=f(w)+f(b)= e) f(x)= -3x
<result>E</result>
For which of the following functions is f(w+b)=f(w)+f(b) for all positive numbers w and b?