Given the task definition and input, reply with output. Answer the question from the given passage. Your answer should be directly extracted from the passage, and it should be a single entity, name, or number, not a sentence.

Passage: In Tibetan Buddhism the teachers of Dharma in Tibet are most commonly called a Lama. A Lama who has through phowa and siddhi consciously determined to be reborn, often many times, in order to continue their Bodhisattva vow is called a Tulku. Question: What has a Lama determined to do?
be reborn