Answer:
A. Circulatory system
Explanation:
Circulatory system consist of heart,blood cells&blood vessels
Alertness is regulated by a group of nuclei (bodies of nerve cells) spread throughout the brain stem and the medulla called the reticular formation.
These nuclei are a relay system that connects the lower parts of the nervous system to the cerebral cortex and integrates signals and information in the brain.
Answer:
Due to muscle contraction and fighting of white blood cells.
Explanation:
Exercise increases the temperature of body because about 20% of the energy produced in contracting muscles is used for muscle contraction while the remaining 80% is converted into heat energy, as a result body's temperature increases whereas a person who has infection also experience high body temperature because the body work faster to fight against the infection that leads to high temperature.