【单选题】

Doctors are starting to find more and more information that suggests a connection between exercise and brain development.According to some research, it seems that exercise can make blood vessels, including those in the brain, stronger and more fully developeD．

The effects of exercise on brain development can even be seen in babies.Babies who do activities that require a lot of movement and physical activity show greater brain development than babies who are less physically active. MargaretBarnes, a pediatrician, believes in the importance of exercise. (82)She thinks that many learning disabilities that children have in elementary school or high school can be traced back to a lack of movement as babies.
In studies with seniors, research has shown that exercise helps older people as well. The exercise doesn’t have to be very difficult. The main goal is just to increase the heart rate.And especially when learning new movements, such as yoga or tai chi, it appears that new memory paths open up in the brain. This can improve people’s short-term memory.
What type of patients does a pediatrician probably treat
A、Patients with mental problems
B．Patients with physical problems
Children
D．Old people