A scientist wants to test whether a herbal supplement decreases reaction time. Reaction times are measured before and after the supplement for each participant. The scientist performs a left-tailed paired $t$-test at the $\alpha =0.05$ level. The test results lead to rejection of the null hypothesis. What is the correct interpretation of this result?

• A. There is not enough evidence to support the claim that the supplement affects reaction time.
• B. There is enough evidence to conclude that the supplement decreases reaction time.
• C. The supplement has no effect on reaction time according to the test.
• D. The supplement increases reaction time based on the test results.