As per the question, the most appropriate prediction that the readers can make about the play after witnessing the given poster would be that 'The poster is dark and wavy, suggesting a theme of mystery' which compliments the thriller setting of the play.
an off-record scource is just uncarted and/or hard to find. however, an anonymous scource has no specific author. someone would prefer to chose to speak to a reperter off the record probanly because they dont want to gain too much attention.
A counterargument is just someone disagreeing with the original argument so they come at them with a counter argument so i would say A. To respectfully address any doubts or objections to the claim.
