Which of the following best describes metalloids?

Metalloids are defined as elements that exhibit properties intermediate between metals and nonmetals. This dual characteristic is what makes them unique in the periodic table. For instance, metalloids can conduct electricity better than nonmetals but not as well as metals, making them semiconductors, which are crucial in electronics. Additionally, they often have physical attributes like a metallic luster and can be brittle, setting them apart from typical metals.

This description aligns perfectly with the nature of metalloids, making it the best choice. The other options do not accurately capture the defining traits of metalloids. Some options, like those that suggest they are highly conductive metals or only exist as anions, mischaracterize their behavior and properties. Others, such as stating that they are reactive nonmetals, fail to encompass the full range of behaviors exhibited by metalloids. Therefore, the ability to show both metallic and nonmetallic properties reinforces why this particular choice is the most fitting description of metalloids.