Final answer:
Smoking increases heart rate, obstructs air and blood flow to the lungs, and decreases skin temperature. The answer is option A.
Step-by-step explanation:
Smoking has several negative effects on the body. When a person smokes, their heart rate increases, which is option a. This is because smoking causes the blood vessels in the skin to constrict, resulting in an increase in heart rate. Additionally, smoking obstructs air and blood flow to the lungs, as stated in option b. This can lead to various respiratory problems. Lastly, smoking decreases skin temperature, as stated in option c. This is because smoking causes sweating, which can result in a decrease in skin temperature. Therefore, the correct answer is option d: all of the above.