Correct Option: A

challenge (Verb) : to refuse to accept something; dispute ; to question whether a statement or an action is right, legal, etc. comply (Verb) : to obey a rule, an order, etc.
complain (Verb) : to say that you are unhappy, annoyed or not satisfied
conform (Verb) : to obey a rule, an order, etc; to comply
compete (Verb) : to take part in a contest/game