The principle which was not preached or followed by Manhatma Gandhi was violence only when absolutely necessary, Option D is correct since Mahatma Gandhi was against any form of violence.
Mahatma followed as well as preached the following principles throughout his life: truth, nonviolence, vegetarianism, brahmacharya (Celibacy), simplicity, faith in God,
Mohandas Karamchand Gandhi was an Indian activist who led the Indian independence movement against British colonial rule.