Why are aerobic activities among the most popular of all activities in the physical activity pyramid?

*will mark brainliest* which of the following best describes a viral infection, such as the common cold? a. virus grow and develop in the body. b. virus are living organisms. c. viruses require host cells in the body. d. viruses can be treated with antibiotics.

Veins have a much lower blood pressure than arteries. which of these prevents backflow of blood in veins? a. pressure applied by the heart b. one–way valves in veins c. thin muscular walls of veins

An alaskan spruce forest will burn easily once burned the forest regenerates fairly wuickly which statement best describes haw an alaskan spruce forest reacts to fire? it is resilient