Which type of radiographic exam uses a magnetic field to induce tissues to emit radio waves?

Magnetic resonance imaging (MRI) is the correct choice because it relies on a strong magnetic field and radiofrequency pulses to create detailed images of organs and tissues within the body. In this process, hydrogen atoms in the body's tissues align with the magnetic field. When radio waves are applied, these atoms are temporarily knocked out of alignment and emit signals as they return to their original state. The emitted signals are then detected and used to construct high-resolution images.

This is distinct from other imaging modalities like computed tomography (CT), which uses X-rays to create images, or traditional X-ray imaging, which relies on radiation to view structures within the body. Ultrasound employs sound waves rather than magnetic fields or radio waves to visualize soft tissues and organs, making its functioning fundamentally different from that of MRI.