How many two-element subsets of {6,7,8,9} are there that do not contain the pair of elements 8 and 9?
Choose the correct choice
A) 5	B) 4	C) 3	D) 6	E) 7

Rationale: required subsets are = { 6,7 } , { 6,8 } , { 6,9 } , { 7,8 } , { 7,9 } = 5 answer : a
Answer: A