The Aajivaka sect, founded by Makkhali Gosala, is primarily known for its strict doctrine of Niyati, which is absolute determinism. This means they believed that everything is predetermined by cosmic forces and that individual effort or karma has no influence on one's destiny or the cycle of transmigration. Thus, statement A (Belief in Determinism) is correct, and statement B (The order of reincarnation can be changed) is incorrect as their doctrine of Niyati implies a fixed cycle. Like other Sramana traditions of the time (Buddhism, Jainism), the Aajivakas also practiced severe asceticism and austerity (tapasya) as part of their path, believing it helped in exhausting the karmic process according to the predetermined sequence; thus, statement C (Belief in Austerity) is correct.