The scores on a statistics test had a mean of 81 and a standard deviation of 9. One student was absent on the test day, and his score wasn’t included in the calculation. If his score of 84 was added to the distribution of scores, what would happen to the mean and standard deviation?

a. Mean will increase, and standard deviation will increase.

b. Mean will increase, and standard deviation will decrease.

c. Mean will increase, and standard deviation will stay the same.

d. Mean will decrease, and standard deviation will increase.

e. Mean will decrease, and standard deviation will decrease.