The Buddhist path to teacherhood ran through the monastic order, so the correct series is made up of the successive monastic statuses a person passed through, not scholarly titles.

Shraman is the first stage. Also called shramanera, this is the novice admitted through the pabbajja ceremony, ordinarily at about eight years of age. The novice left home, took the ten precepts and studied under a preceptor.

Bhikkhu is the second stage. At about twenty, after the required years of novitiate, the novice underwent upasampada, the higher ordination, and became a full monk of the sangha, bound by the complete Vinaya discipline.

Upadhyaya is the third stage. After roughly ten further years as a bhikkhu, one of proven learning and conduct could be recognised as a preceptor, entitled to ordain and instruct novices of his own. This is the position of the guru in the Buddhist system.

The other three sequences mix in terms that do not belong to this progression. Shravak denotes a lay follower who listens to the teaching, and so lies outside the monastic ladder altogether. Brahmachari, Pandit and Shishya belong to the Brahmanical or general scholarly vocabulary rather than to the Buddhist monastic order.

Hence the series is Shraman, Bhikkhu, Upadhyaya.