Explanation:

Only statements 2&3 are correct.

• It is central to the Mahayana sect of Buddhism.

• In non-Mahayana Buddhism, it usually refers either to Maitreya, the Buddha of the Future, or to the historical Buddha Gautama prior to his enlightenment.

• A bodhisattva is literally a living being (sattva) who aspires to enlightenment (bodhi) and carries out altruistic practices. The bodhisattva ideal is central to the Mahayana Buddhist tradition as the individual who seeks enlightenment both for him- or herself and for others. 

• Compassion, an empathetic sharing of the sufferings of others, is the bodhisattva’s greatest characteristic.

• It is held that the bodhisattva makes four vows expressing a determination to work for the happiness of others: “However innumerable sentient beings are, I vow to save them; however inexhaustible the passions are, I vow to master them; however limitless the teachings are, I vow to study them; however infinite the Buddha-truth is, I vow to attain it.”

Hence option 2nd is correct.