The correct answer is tolerance.
The concept that best summarizes the beliefs of Ashoka was tolerance.
Ashoka the Great (304-232 BCE) was the ruler of the Mauryan Empire. He was considered a good Emperor for the ideas he spread about Buddhism. After being a cruel ruler, he changed his mind and started to focus on dharma. He converted to Buddhism and issued the edicts of Ashoka where he included ideas such as religious freedom, tolerance of different beliefs, ask obedience to the parents, instructs his officials to help the poor and to help the elderly, among others.
The other options of the question were, a) persecution, c) power, d) self-control.