Explain me science in detail​

Which two levels of the spine that can undergo flexion and extension?

The maximum blood pressure in the upper arm of a healthy person is about 120 mmhg. if a vertical tube open to the atmosphere is connected to the vein in the arm of the person, determine how high the blood will rise in the tube. take the density of the blood to be 1040 kg/m3.

As you sit in the library with your friend studying for your weekly quiz on the integumentary system, you come upon an article about the hazards of prolonged exposure to the sun's rays. your curious nature leads you to research the subject further. you're fascinated to learn that minimal exposure to the sun allows you skin to manufacture vitamin d, which is important to maintain homeostasis. you also read that although sunscreen can protect you from the ultraviolet (uv) rays of the sun, some medications can actually increase a person's sensitivity to the sunlight.