In this task, you need to answer the given multiple-choice question on geometry. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.
Q: Problem: people were sitting in a circle . 7 th one is direct opposite to 18 th one . . then how many were there in that group ?
Options: ['a ) 21', 'b ) 22', 'c ) 23', 'd ) 24', 'e ) 20']
A:
b