He is really an obstinate man.

Answer: Option D

Obstinate : stubbornly refusing to change one's opinion or chosen course of action, despite attempts to persuade one to do so.
Considerate : careful not to inconvenience or harm others.
Friendly : kind and pleasant.
Understanding : the ability to understand something; comprehension.
Compliant : disposed to agree with others or obey rules, especially to an excessive degree; acquiescent.

Antonym of Obstinate is Compliant