How many two-element subsets of \(\{1,2,3,4\}\) are there that do not contain the pair of elements \(2\) and \(4?\)

[M7MBA]

How many two-element subsets of \(\{1,2,3,4\}\) are there that do not contain the pair of elements \(2\) and \(4?\)

(a) One
(b) Two
(c) Four
(d) Five
(e) Six

Answer: D

Source: Official Guide