Correct Answer - Option 3 : 28
First person shakes hand with seven other persons. Second person shake hand with six other person because he has already shook hands with first person. Similarly, third person will shake hands with five other persons and so on.
The number of possible hand shakes is = 7 + 6 + 5 + 4 + 3 + 2 + 1 = 28
Hence, option 3 is the correct answer.