Q20: Is $\{(1, x), (2, y), (3, z)\}$ a bijection from $\{1, 2, 3, 4\}$⁠?

In the following questions, a statement of Assertion (A) is followed by a statement of Reason (R). Choose the correct answer out of the following choices.

(a) Both (A) and (R) are true and (R) is the correct explanation of (A).

(b) Both (A) and (R) are true but (R) is not the correct explanation of (A).

(c) (A) is true but (R) is false.

(d) (A) is false but (R) is true.

ASSERTION (A): The relation $f : \{1, 2, 3, 4\} \to \{x, y, z, p\}$ defined by $f = \{(1, x), (2, y), (3, z)\}$ is a bijective function.

REASON (R): The function $f : \{1, 2, 3\} \to \{x, y, z, p\}$ such that $f = \{(1, x), (2, y), (3, z)\}$ is one-one.