How many pairs t, t+1) have one or more prime factors common, where t is an integer and 2 ≤ t ≤9 ? Choose the correct option
A) 0 B) 1 C) 2 D) 3 E) 4
t and t+1 are consecutive integers.   Two consecutive integers are co-prime, which means that they don't share ANY common factor but 1. For example 20 and 21 are consecutive integers, thus only common factor they share is 1.   0nswer: 0.
<result>A</result>
How many pairs t, t+1) have one or more prime factors common, where t is an integer and 2 ≤ t ≤9 ?