Here we have 2 groups one 4 members having one friend each and the other with 3 members having 2 friends each. probablity of selecting a group is 1/2

for the first we can select 2 people such that they are friends in 4*1=4 ways

Then for second group we get 3*2=6

sum =1/2 *(4+6)=5

no of ways to select 2 persons at random is 7c2=21

Probability that couple selected are friends is 5/21

Not friends =1-5/21=16/21

What is OA?

Also does anyone has a simpler method to solve

Using the golden pair rule i was able to eliminate 3 of the five answers but taking the right between those took time