Which of the followings is correct about class action lawsuits?

a)To obtain certification, the class must have common legal and factual claims.

b)To maintain a class action lawsuit, class members should be at least 50 members.

c)To obtain certification, the class must claim $5 million or more.

d)To maintain a class action lawsuit, the separate lawsuits by individual class members should stem from thesamefact situation.