Question 6 Suppose we want to prove the statement Vay ER, P(x, y) (assume that we've previously defined a predicate P). Which of the following statements could we use to introduce z and y in our proof header Let I be an arbitrary real number, and let y = 1 +1. Let z = 1 and y=3. Letz, y ER Let 2 and y be arbitrary real numbers. Let zand y be arbitrary real numbers such that P(z,y) is true