Which disease is mainly characterized by arterial stiffness and thickening?

Arteriosclerosis is primarily characterized by the thickening and stiffening of the arterial walls. This condition affects the elasticity of the arteries, leading to reduced blood flow and an increased risk of cardiovascular events. The thickening occurs due to the buildup of fatty deposits, cholesterol, and other substances within the arterial walls, which make arteries less flexible. Over time, this can lead to more severe cardiovascular issues such as hypertension, heart attacks, or strokes.

In contrast, endocarditis refers to the inflammation of the inner lining of the heart, myocardiac involves inflammation of the heart muscle itself, and leukemia is a cancer of the blood-forming tissues. While these conditions may affect the cardiovascular system, they do not primarily involve the stiffness or thickening of arterial walls in the same manner as arteriosclerosis. Therefore, the specific characteristics associated with arteriosclerosis make it the correct answer for this question.