Which of the following blood elements is involved in protecting the body from pathogens?

a. Elastic connective tissue: This tissue contains elastic fibers and fibroblasts, providing elasticity and flexibility but not the tightly packed, parallel collagen fiber arrangement.

b. Dense irregular connective tissue: This tissue has collagen fibers arranged in a random, irregular pattern, providing strength in multiple directions but not the parallel arrangement.

c. Reticular connective tissue: This tissue contains reticular fibers forming a network to support soft organs but does not have densely packed collagen fibers.

d. Dense regular connective tissue: This tissue has fibroblasts packed tightly between parallel arrays of collagen fibers, providing great tensile strength along the direction of the fibers. It is found in tendons and ligaments.

a. The right ventricle chamber has a smaller overall capacity than the left ventricle: While true, this doesn't directly explain the difference in muscle thickness.

b. The right ventricle receives blood from right atrium, which has lower pressure than left atrium: Both ventricles receive blood from low-pressure atria. The pressure difference is between the circulation systems they pump blood into.

c. The right ventricle pumps a smaller blood volume than the left ventricle. The right ventricle pumps blood to the lungs, a low-pressure system. Therefore, the right ventricle wall (myocardium) is thinner than the left ventricle wall. The left ventricle pumps blood against the higher resistance of the systemic circulation, so its wall is much thicker and stronger.

d. The right ventricle pumps blood into pulmonary circulation, which has lower resistance than systemic circulation: This is the core reason for the difference in muscle thickness.