In a debate you need to formulate arguments, but these arguments will have no value if you do not use facts to prove them. The author of arguments for a speech, based on concrete evidence, must present consistent facts for the construction of argumentative thinking that will be defended or refuted in a debate.
B, because if you don't have anything to back up the argument then you will not have a steady argument making the "debate" on your side turn into an opinion.
