Short Answer
Strongly attenuate X-rays (high atomic number — e.g., iodine, barium) is the best answer.
Biophysics questions work best when you translate anatomy or instrumentation back into plain physics: pressure gradients, flow, diffusion, energy deposition, imaging contrast, and signal-to-noise.
Iodine (Z=53) and barium (Z=56) have large photoelectric cross-sections, dramatically attenuating X-rays in blood vessels or the GI tract.
Why This Answer Is Correct
This is a Easy-level question in Biophysics & Medical Physics. The prompt is really testing whether you can connect the concept to its defining physical relationship instead of picking a nearby-but-wrong term.
Clinical wording can hide a simple physics core. Strip the scenario down to transport, force, energy, or measurement first.
Choices At A Glance
- A. Emit radiation
- B. Strongly attenuate X-rays (high atomic number — e.g., iodine, barium)
- C. Reflect ultrasound
- D. Fluoresce in MRI
When similar options appear on an exam, eliminate the ones that break the core law, use the wrong units, or confuse a definition with a consequence.
Study Next
Review the related formula library
study the medical physics track
Topic Snapshot
Topic: Biophysics & Medical Physics
Difficulty: Easy
Best next move: Re-state the governing law in your own words, then solve one more example from the same topic before moving on.