Aman, a lawyer was suspended as he breached the rules laid down by the Bar Council of India. From the options given below, what misconduct may have led to his suspension?
a. He charged contingency fee from his client in a land dispute.
b. He negotiated with the opposite party through the opposing advocate.
c. He refused to represent client who insisted on adopting unfair means.
d. He refused to appear in a matter where he was the witness.