In human body "A" is a pumping organ. From lungs blood vessel "B" with oxygenated blood enters upper "C" Part of left chamber of the organ. When " C" chamber contracts blood flows into "D" lower left Chamber. Contracts blood is pumped to all parts of the body except lungs through blood vessel E. Deoxygenated blood from body parts is collected by blood vessel "F" and opens upper "G" right chamber. This chamber contracts blood flows "H" lower chamber. Lastly "H" contracts De-ozygenated blood sent to lungs by blood vessel "I".
What organ does 'A' represents ?

Explanation

Heart