Answer:
The correct answer is A) Polycythemia vera
Step-by-step explanation:
Erythrocytosis is referred to as the extra and increased production of RBC and it primarily occurs due to the result of a disease called Polycythemia Vera.
Polycythemia vera is a disease or slowly growing blood cancer in which bone marrow makes excess of hemopoietic cells(RBC, WBC, platelets). These excess cells results in thickening of blood and slowing the flow of blood which can cause clotting of blood that can lead to heart stroke or heart attack.
Therefore polycythemia vera is the disease that shows the primary characteristics of erythrocytosis and some times these two terms are used interchangeably.