The answer is Right atrium.
The human heart is a four-chambered muscular organ which pumps blood to the entire body. The two upper chambers are atria (singular atrium) and two lower chambers are ventricles. The left and right sides of the heart are separated by a muscular septum. The right and left atria are the 'receiving' chambers of the heart and ventricles are 'distributing' chambers. The right atrium receives deoxygenated blood from all parts of the body and the left atrium receives oxygenated blood from the lungs.