Answer:
the last choice.
Explanation:
veins have valves because venous pressure is often not great enough( as the blood must overcome gravity and other forces) to return the blood to the heart.
valves mainly prevent the back flow of blood.
The correct answer is choice 2. tumors that grow fast and spreading to neighboring tissues. Malignant tumors or cancerous tumors are tumors that grows and multiply to become cancer overtime. This tumors are due to the high unstable abnormal cells that travels in the blood stream.
AIDS stands for Acquired Immune Deficiency Syndrome:
→<span>Acquired means you can get infected with it;Immune
</span>→<span>Deficiency means a weakness in the body's system that fights diseases.
</span>→<span>Syndrome means a group of health problems that make up a disease.</span>
AIDS is caused by a virus called the Human Immunodeficiency Virus (HIV). If you get infected with HIV, your body will try to fight the infection. It will make "antibodies," special immune molecules the body makes to fight HIV.
Answer: C. clean with soap and water
Explanation: all the rest are unsanitary
Answer:the answer is
compilation of professional..
Explanation: