What is a key characteristic of rodents?

A key characteristic of rodents is their continuously growing incisors that require constant gnawing. This defining feature is crucial for their survival, as the teeth can grow several inches in a year. If they do not gnaw on hard materials like wood, nuts, or other foods, their teeth can become overgrown, leading to difficulties in eating and potential health issues. This constant gnawing behavior also helps them keep their teeth at a manageable length, which is essential for their daily activities and feeding habits.

The other options do not accurately represent core characteristics of rodents. For instance, they do not typically have colorful markings; rather, many have more muted colors that provide camouflage in their natural habitats. Additionally, rodents are known for their rapid reproduction rates, which is one of the reasons why their populations can grow quickly in the right conditions. Lastly, while some rodents may inhabit trees, many species live in a variety of environments, including underground burrows and urban areas, making tree-dwelling a less defining characteristic.