Infected cells can release chemicals that travel through the bloodstream to alert

the brain. the brain then sends signals along [veins; muscles; nerve cells;

bones] to increase the temperature of the body. white blood cells are brought into

the infected area using the [digestive system; respiratory system; circulatory

system; endocrine system]. based on the graph, the infected area most likely

stops releasing chemicals to alert the brain of an infection [2 hours; 3 hours;

5 hours; 7 hours] after the infection starts.

veins; digestive system; 2 hours

muscles, respiratory system; 4 hours

nerve cells; circulatory system; 5 hours

nerve cells; endocrine system; 7 hours