When a virus invades a host the most common threat is
a. production of viral fluids in the bloodstream.
b. fermentation of acids in the digestive system.
c. destruction of cells by viral reproduction.
d. stimulation of muscle tone in the heart.

answer; ///(b) it is composed of four protein chains and four heme groups;

explanation:

the universal gravitation equation. since the gravitational force is directly proportional to the mass of both interacting objects, more massive objects will attract each other with a greater gravitational force. if the mass of one of the objects is doubled, then the force of gravity between them is doubled.