Explanation
Why Correct: The original name of the sect that later became Jainism was Nigranthas, meaning 'free from bonds' or 'unfettered ones,' referring to ascetics who had overcome worldly attachments.
Distractor Analysis: Tirthankaras are the 24 spiritual teachers in Jainism, starting with Rishabhanatha and ending with Mahavira. Jina means 'victor' or 'conqueror,' a title given to those who have achieved spiritual victory, from which 'Jain' derives. Arhant means 'worthy one' or 'perfected being' who has attained enlightenment.
Takeaway: Mahavira, the 24th Tirthankara, systematized and propagated the Nigrantha tradition, which evolved into Jainism around the 6th century BCE.