The correct answer is A. Rishabhnath.
Rishabhnath is the first Tirthankara of the present age. He is also known as Adinath, Prajapati, and Aadinath. He is said to have lived for 84 lakh years and attained nirvana at Mount Ashtapada.
Ajitnath is the second Tirthankara of the present age. He is said to have lived for 84 lakh years and attained nirvana at Mount Sammed Shikhar.
Sambhavnath is the third Tirthankara of the present age. He is said to have lived for 84 lakh years and attained nirvana at Mount Shatrunjaya.
Abhnindan Nath is the fourth Tirthankara of the present age. He is said to have lived for 84 lakh years and attained nirvana at Mount Girnar.
Rishabhnath is the most important Tirthankara in Jainism. He is the first Tirthankara of the present age and is said to have founded Jainism. He is also the first Tirthankara to have attained nirvana. Rishabhnath is considered to be the most perfect of all the Tirthankaras and is the most revered by Jains.