It is so important because complex carbohydrates give you the most energy
Answer:
B. left atrium and C. left ventricle
The nucleus is still there.
Following the requirement of question I have attached a picture of phylogenetic tree.
Here is the source publication PNAS June 26, 2012 109 (26) 10293-10297
The correct answer is A, positively, it helps to diagnose heart disease.
An electrocardiogram records the electrical activity of your heart at rest. It provides information about the heart rate and rhythm, and shows if there is enlargement of the heart due to high blood pressure or evidence of a previous heart attack.