Extracted text: QUESTION 10 Which of the following relations also define a function from A to B? A fa, b, c, d), B {1, 2, 3) {(a, 1), (b, 2), (c. 1), (d, 2) R (1, 2, 3) (a, b, c, d), B R {a, 1), (b, 2), (a, 2), (c, 1), (d, 2) A A set of all recipients of Medicare in the United States B x | x is a nine-digit number aRb iff b is a's Social Security Number