Well this is one of question, where you don't require any data.
Question is:
number (members attending yoga sessions) > number (members attending strength training sessions)
Statement 1:
If 20 members attend yoga session, then they should at least take one other type of session.
Possibility 1: 20 members attend strength training sessions
Then: number (members attending yoga sessions) = number (members attending strength training sessions) =>
False Possibility 2: 30 members attend strength training sessions
Then: number (members attending yoga sessions) < number (members attending strength training sessions) =>
False Possibility 3: 10 members attend strength training sessions
Then: number (members attending yoga sessions) > number (members attending strength training sessions) =>
TrueSo, nothing can be inferred here.
Statement 2:
If 20 members attend yoga session, then they should also attend strength training sessions.
Possibility 1: 20 members attend strength training sessions
Then: number (members attending yoga sessions) = number (members attending strength training sessions) =>
False Possibility 2: 30 members attend strength training sessions
Then: number (members attending yoga sessions) < number (members attending strength training sessions) =>
FalseSo, we can infer from statement 2 alone, number of members attending yoga sessions cannot be greater then number members attending strength training sessions.
So answer is
B