Final answer:
Pulmonary stenosis is a narrowing of the pulmonary valve, which obstructs the flow of blood from the right ventricle to the lungs.
Step-by-step explanation:
Pulmonary stenosis is a narrowing of the pulmonary valve. The pulmonary valve is located between the right ventricle and the pulmonary artery, allowing blood to flow from the right ventricle to the pulmonary artery. Stenosis of the pulmonary valve can obstruct the flow of blood from the right ventricle to the lungs, leading to symptoms such as shortness of breath and fatigue.