The question needs to find whether members of yoga sessions are more than members of strength training sessions.
Statement 1
Every member who attends yoga sessions also attends at least one other type of session.
This doesn't clarify whether other type of session is Strength sessions or other as well. No clarity on no. of members for strength training sessions.
Hence statement is insufficient.
Statement 2
Every member who attends yoga sessions also attends strength training sessions.
It is clear that as many people does Yoga sessions also does Strength training sessions.
Clearly more members will be in Strength Training sessions.
So answer of the question is no the members of yoga sessions are more than members of strength training sessions.
Statement 2 is sufficient.
Correct answer is B.