Final answer:
Air will absorb the fewest X-rays because it has much lower density and atomic number than bone, water, or muscle, making it the least absorptive material for X-ray imaging.
Step-by-step explanation:
You asked which of the following will absorb the fewest X-rays: A. Bone, B. Air, C. Water, or D. Muscle. The answer is B. Air. The absorption of X-rays is determined by the material's density and atomic number. Since air is much less dense than bone, water, or muscle, it absorbs the fewest X-rays. Bone has a high density and a higher atomic number, which makes it absorb X-rays effectively, showing up as white on an X-ray image. Water and muscle have similar densities and absorb X-rays to a greater extent than air, but less than bone.
X-rays are used in imaging because they have higher penetrative energy than radio waves, allowing them to pass through soft tissues and be absorbed by denser materials, like bone, which creates a contrast useful for imaging structures within the body.
Radiation shielding principles also dictate that materials like air, being less dense, would provide less shielding against radiation compared to denser materials such as lead, commonly used in protective aprons during X-ray procedures.