[Solved] Sroufe and Rutter have suggested that the child focuses on different aspects of the environment at different times. At which age does the child focus on the biological world? A) 0 to 1 years B) 1 to 2-1/2 years C) 3 to 5 years D) 6 to 12 years E) 13 or more years Sinoatrial Node: A group of cells in the right atrium of the heart that initiates the electrical impulses determining the heart rate, often called the heart's natural pacemaker. Atherosclerotic Changes: Alterations in blood vessels characterized by the accumulation of fatty deposits along their inner walls. Internal Bleeding: Bleeding within the body that can result from injury or illness, potentially leading to serious health complications without immediate treatment. Perfusion: The passage of fluid through the circulatory system or lymphatic system to an organ or a tissue.