Two ways to turn the step function into a continuous function that approximates a step function are the (logistic) sigmoid s and the hyperbolic tangent t. Suppose a node has a weighted sum of inputs x. There is a relatively simple relationship between s(x) and t(x). Your task is to determine what t is, as a function of s (not x), and then identify the true statement below.

a) If s = 3/10, then t = -2/3.
b) If s = 1/5, then t = -13/15.
c) Ifs = 3/10, then t = -15/22.
d) If s = 3/5, then t = 5/13.