The rate at which blood flows through the human body changes in response to many factors. which statement describes one of these factors and its effect on blood flow? a a high viscosity of blood causes an increased resistance in the blood vessels and leads to slow blood flow. b a low blood ph decreases the rate of diffusion through the blood vessels and leads to slow blood flow. c the changing of the shape of red blood cells to a crescent shape decreases resistance and lead to a faster blood flow. d the narrowing of blood vessels increases pressure and leads to a faster blood flow.