Correct Option: A

denial (Noun) : a statement that says something is not true or does not exist
affirmation (Noun) : statement asserting the existence or the truth of something
opposition (Noun) : the act of strongly disagreeing with somebody or something, with the aim of preventing something from happening
refusal (Noun) : an act of showing or saying that you will not do, give or accept something
obstruction (Noun) : the fact of trying to prevent something/ somebody from making progress; blocking a road, an entrance, a passage, etc ; blockage