The correct options are
A It was an association for the people who left their homes.
B Vinaya Pitaka contained rules for the Buddhist sangha.
C Residents of the sangha were known as bhikkhus.
Sangha was an association for the people who left their homes in search of true knowledge. A book called the Vinaya Pitaka contained rules for the Buddhist sangha. People of any background were allowed to be members. Residents of the sangha were known as bhikkhus.