Which valve is present between the left atrium and the ventricle?
A. Tricuspid
B. Mitral
C. Aortic
D. Pulmonary.

Hint: Heart is the muscular organ that is present in between the lung on the left side near the cardiac notch of the lungs, it pumps the blood throughout the body via different arteries and receive the blood via veins, heart perform the circulatory system of the body.

Complete answer:
Human heart is four-chambered and divided into the left atrium, left ventricle, and right atrium, and right ventricle. The left part of the heart pumps the blood to the whole body so its left ventricle is thick while the right part of the heart receives deoxygenated blood and sends it to the lung for the oxygenation purpose.
A. Tricuspid valves guard the right atrioventricular opening, which is three flaps present in between the right atrium and right ventricle, these valves prevent the backflow of blood.
B. Mitral valves are also called a bicuspid valve, this valve guards the opening of arterial-ventricular opening and prevents the backflow of blood from ventricles to atrium.
C. Aortic :- it is related to the aorta which is the bigger or larger blood artery that arises directly from the heart which bears aortic arteries which send oxygenated blood to the different parts of the body.
D. Pulmonary:- it is related to lungs, pulmonary trunk arises from the right ventricle that carries deoxygenated blood to the lung for the oxygenation of the blood.
Hence, the correct option is B.

Note:Heart is the most important vital organ that pumps blood which acts as transport medium which carries nutrients, minerals, hormones, enzymes, and other unnecessary byproducts which mean to excrete out from the body via excretion process.