The answer would be <span>B) </span>Sternomastoid and trapezius :)
Answer:
Alaska
Explanation:
Alaska has the most active volcanos in America.
The correct answer is option D, that is since genetic drift is random, it does not always favor the better or healthier organisms.
A mechanism of evolution in which the frequencies of alleles of a population change with generations because of sampling error is known as genetic drift. It takes place in all the populations of non-infinite size, however, its influences are strongest in small populations.
Answer: B. pressure changes in the thorax
Explanation:
The veins are the blood vessels which returns the deoxygenated blood from all the tissues and cells of the body back to the heart. The ventricular systole, venous valves, activity of the skeletal muscles and neural control over venoconstriction all influence the movement of the blood in the venous.
The pressure changes in the thorax occurs due to inspiration and expiration. During the process of inspiration, the diaphragm below the lungs contracts and moves downward while the muscles of the ribs pulls downward. When the size of the thoracic cavity increase the air pressure inside the cavity decreases and vice-versa. The pressure inside the thoracic cavity is not related with the movement of the venous blood as it regulates the exchange of the gases not the blood.
