Which one of the following equations involving the delta function is incorrect?
a) δ(t) * f(t) = f(0) * δ(t)
b) δ(t) * f(t) = f(t)
c) f(t) * δ(t) = f(0) * δ(t)
d) δ(t) * f(t) = δ(t) * f(0)