The correct answer is: A. Bhadrabahu
Bhadrabahu was a Jain monk who lived in the 2nd century BCE. He is credited with the spread of Jainism in Karnataka, south India. He was a disciple of the 23rd Tirthankara, Parshvanatha, and he is said to have converted many people to Jainism. He is also said to have written several important texts on Jainism.
Adinatha was the first Tirthankara, or Jain prophet. He is said to have lived in the 9th century BCE. He is credited with founding Jainism and with establishing the basic principles of the religion.
Parshvanatha was the 23rd Tirthankara. He is said to have lived in the 8th century BCE. He is credited with reforming Jainism and with making it more accessible to the common people.
Mahavira was the 24th and last Tirthankara. He is said to have lived in the 6th century BCE. He is credited with bringing Jainism to its peak and with making it a major religion in India.
Bhadrabahu is the most likely answer to the question because he is the only one of the four options who is specifically credited with the spread of Jainism in Karnataka. Adinatha, Parshvanatha, and Mahavira were all important figures in Jainism, but they are not specifically associated with the spread of the religion in Karnataka.