What is a primary advantage of using a toroidal core instead of a solenoidal core in an inductor?

A toroidal inductor is wound on a donut-shaped core. Because the magnetic path is a continuous closed loop, nearly all of the magnetic flux remains confined within the core material itself, effectively making the inductor self-shielding. Because the magnetic field is contained, the inductor is prevented from causing unwanted magnetic coupling or crosstalk with nearby components in tightly packed RF circuits. By contrast, a standard solenoidal (straight cylindrical) core allows its magnetic field to radiate outward into the surrounding space. Controlling stray coupling is the primary advantage. The incorrect options suggest undesirable traits; for a high-performance inductor, you generally want higher Q (quality factor) and lower hysteresis (energy loss).