A pharmaceutical company has developed a new drug to help relieve acid reflux. However, as with all new drugs, there are concerns about adverse side effects. To check this, the company administers the drug to n randomly chosen people with acid reflux, and it finds that k of them experience adverse side effects. The company hopes to reject the null hypothesis that the proportion of drug-takers who experience adverse side effects is at least 0.5%. Which of the following is true?

a. If n=1,250 and k=1, this is enough evidence to reject the null at the 1% level.

b. If n=4,000 and k=9, this is enough evidence to reject the null at the 1% level.

c. If n=1,600 and k=4, this is enough evidence to reject the null at the 5% level.

d. If n=1,000 and k=3, this is enough evidence to reject the null at the 10% level.