If a person has lost a significant amount of blood but still maintains a normal blood pressure it does not necessarily mean that the person is maintaining adequate perfusion. Which of the following best explains why this is so?
a. Blood vessels are constricting causing greater peripheral resistance.
b. The heart has increased its rate to increase cardiac output.
c. The sympathetic nervous system has increased its nerve impulses.
d. The heart has increased its contractile force increasing cardiac output.