A. Preparation i think I’m sorry if it isn’t right
Answer:With this system, blood always flows in only one direction inside the heart. There are also valves at the bottom of the large arteries that carry blood away from the heart: the aorta and the pulmonary artery. These valves keep the blood from flowing backward into the heart once it has been pumped out.
Explanation:
True. Being abstinent is the only form of STD preventive that is 100% affective.
Answer:
all I know is that A is true and B is too hope this somehow helped
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