In ancient Indian Buddhist monasteries, the ceremony called Pavarana was the occasion for monks to confess their offenses committed during their stay in the monasteries during the rainy season.

During the rainy season retreat, known as Vassa or Varsha, Buddhist monks would stay in one place and engage in intensive meditation and study. At the end of this retreat, the Pavarana ceremony was held. During this ceremony, the monks would gather and individually confess any offenses or transgressions they had committed during the retreat.

Confession of offenses was an important practice in Buddhism, as it allowed the monks to purify themselves and renew their commitment to the monastic code of conduct, known as Vinaya. The Pavarana ceremony provided an opportunity for monks to openly acknowledge their mistakes and seek forgiveness from the monastic community.

Therefore, the correct statement is: Pavarana was the occasion for monks to confess their offenses committed during their stay in the monasteries during the rainy season.