if f is a differentiable function satisfying f(1/n)= 0 for all n 1,n integers, then

a) f(x)=0

b) f '(0)=0=f(0)

c)f(0)=0 but f '(0) not necessarily zero

d) | f(x) | 1, x  (0, .1]

i think a and b are the right options!

am i right?