A. What are the marginal probability mass functions Pr[X1 = s] and Pr[X2 = t]? B. What are the expected values E[X ] and E[X2]? C. Are the random variables X1 and X2 independent or not? Justify your answer. D. What are the conditional probability mass functions Pr[X1 = s | X2 = 1] and Pr[X2 = t | X1 =6]? E. What is the conditional expected value E[Xi | X2 = 3]? [FYI] Markdown template for univariate mass function (e.g., questions A and D), for your convenience. Please make sure to modify as appropriate (e.g., variable names