Doctors conducting a pharmaceutical study release the following information: . The probability that a patient will receive a trial medication in the first round is I; . The probability that a patient will receive a placebo medication in the second round given that they received a trial medication in the first round is 3: . The probability that a patient will receive a placebo medication in the second round is Let event A be the event that a patient receives a trial medication in the first round and event B be the event that a patient receives a placebo medication in the second round. Are events A and B mutually exclusive, independent, both, or neither