Question

Blood group system in human being is controlled by-
A. Gene
B. Brain
C. Heart
D. Veins

Answer 1

The study of blood in health and disease is known as hematology. It includes problems with the red blood cells and white blood cells, platelets, blood vessels, bone marrow, lymph nodes, spleen and all the proteins involved in bleeding and clotting factors. Hemostasis and thrombosis. Red blood cells life span is said to be $120$ days while white blood cells have shorter life span about $45$ days.

Complete explanation:
Hematology as we discussed is the study of blood and blood producing organs and cells. Blood as we know is carried in vessels known as blood vessels. Blood vessels which carry deoxygenated blood from other parts of the body to the heart are called veins. Veins carry carbon dioxide in the blood except for pulmonary vein that carries oxygenated blood from lungs to heart. Arteries carry oxygen rich blood into the heart and lungs and other body parts while veins carry deoxygenated blood from other parts of the body.
Option A Gene: Genes are short sequences of DNA, deoxyribonucleic acid packed in long strands of DNA. Many strands of DNA form chromosomes and they are tightly packed with proteins inside a cell. Genes contain all the genetic information which are being transferred from generation to generation. The type of human blood is determined by codominant alleles. For human blood groups there are three distinct alleles- IA, IB and I.
So, option A is correct.
Option B Brain: Brain is the central working system of our body. It controls and coordinates all the functions of our body. But it does not determine the blood grouping in humans.
So, option B is not correct.
Option C Heart: Heart is a muscular and important organ or major organ of the body. It comes under the circulatory system as its function is to pump blood throughout the body. If a heart stops working the person could die. It is that essential organ. The heart is about the size of our fist located behind and slightly left of the breastbone. Functions of the heart includes pumping oxygenated blood to the other body parts.
So, option C is not correct.
Option D Veins: Veins are the blood vessels that deliver blood throughout the body and to various organs. The atria-ventricular node is a part of the heart's electrical conduction system that coordinates the heart's top. From the atria to the ventricles, it transports the usual electrical impulse.
So, option D is not correct.

Hence, Option A is the correct answer.

Note:
As we discussed the major components and location where blood is being synthesized. There are also some facts in blood as- blood constitutes ninety percent of water and ten percent of these components. Water helps blood in maintaining its fluidity, otherwise blood can clot in the body due to a high amount of different clotting factors. So, it is essential for water balance in the body in order to keep blood flow balanced.