The correct answer is option 1: "1 only."

Option 1 states that Bodhisattas were perceived as deeply compassionate beings who accumulated merit through their efforts. This statement is correct. Bodhisattas are known as beings who have reached a high level of spiritual development and have chosen to postpone their own enlightenment in order to help others achieve liberation from suffering. They are seen as embodying compassion and selflessness, and their actions are driven by the desire to benefit all sentient beings. The accumulation of merit is an important aspect of their path, as it is believed to contribute to their eventual enlightenment.

Option 2 states that Bodhisattas made attempts to attain Nibbana (also known as Nirvana). This statement is incorrect. Bodhisattas are on the Mahayana Buddhist path, which differs from the Theravada Buddhist path. In Mahayana Buddhism, Bodhisattas aim to become fully enlightened Buddhas in order to benefit all beings. They do not seek personal enlightenment or attain Nibbana for themselves.

In summary, only option 1 is correct.