Both does not burn the same amount of calories. Running exert more effort than walking. And that makes running to burn more calories that walking. Not unless you walk more more miles away and run only in a short time.
Thus letter D. is not a true statement
The immediate effects of exercise are on the neurotransmitters. They cause the signals that pass through the brain go faster. This makes it easier for you to learn new things. Since exercise makes muscles stronger, cells are created in the process and it increases the number of pathways for oxygen and other things. That makes your reflexes and your nerves faster. Different types of exercises also increase your cognitive learning.
Hope this helps :)
Because each culture has its own sets of beliefs and disbeliefs that can influence a person.