Let Yand X be two random variables and let E (Y|X) conditional expectation function. Which of the following is true for the law of iterated expectations ? 1. The law says that if we take the expectation over all the values that we first condition on, we obtain the unconditional expectation II. E[E(Y|X)] = E (Y) III. E(Y) is the probability weighted average of all the conditional means of Y given X Select one: a. None of the options O b. I, II, III O c. 1, 11 O d. 1 O e