According to the Focus on Neuroscience Box "Boosting the Aging

According to the Focus on Neuroscience box "Boosting the Aging Brain" aerobic exercise had which of the following effects on the hippocampus in older adults?

A) Aerobic exercise resulted in a 1.4 percent decline in hippocampal volume over a one-year period.
B) Aerobic exercise resulted in an 80 percent increase in hippocampal volume over a one-year period.
C) Aerobic exercise resulted in a 2 percent increase in hippocampal volume over a one-year period.
D) Aerobic exercise improved memory but did not measurably affect the hippocampus.