Correct answer: B. Twenty-fourth
Explanation: The governing concept is the Jain tradition of twenty-four Tirthankaras, teachers who are understood to have shown the path to spiritual liberation. Mahavira, also known as Vardhamana, is regarded in Jainism as the twenty-fourth and last Tirthankara of the current cycle. Therefore option B is correct. Rishabhanatha, or Adinatha, is traditionally identified as the first Tirthankara, so option A confuses Mahavira with the earliest figure. The tenth and sixteenth positions belong to other Tirthankaras, making options C and D incorrect. Mahavira is especially important because he systematised and widely taught Jain principles such as non-violence, truth, non-stealing, non-possession and celibacy. The number twenty-four is the key fact required here.