The results of a large 6 year study on an HIV vaccine were announced in September, 2009. The study was conducted in Thailand. 51 out of 8197 people in the vaccine arm of the trial became infected with HIV, compared with 74 out of 8198 people who received a saline placebo shot. Researchers reported a P-value of 0.04 regarding the difference in the proportion who contracted HIV after treatment. Identify the correct interpretation of the P-values. CHOICES: A. There is a 4% chance the HIV vaccine does not work OR B. The difference observed in the proportion who contract HIV after vaccination versus placebo would happen only 4% of the time if the vaccine really didn't work.