John Milton wrote 'Paradise Lost' to vindicate the ways of God to man.

Answer: Option C

Explain : make (an idea or situation) clear to someone by describing it in more detail or revealing relevant facts.
Support : bear all or part of the weight of; hold up.
Justify : show or prove to be right or reasonable.
Criticise : indicate the faults of (someone or something) in a disapproving way.
Vindicate : show or prove to be right, reasonable, or justified.

Synonym of Vindicate is Justify