An injury that develops slowly, is persistent, and is long-lasting is referred to as:

The term that describes an injury developing slowly, persisting over time, and lasting for an extended period is "chronic." Chronic injuries are often the result of repetitive motions, ongoing stress on certain body parts, or underlying health conditions. They can vary in severity but are characterized by their long duration and ongoing symptoms that may not respond immediately to treatment.

In contrast, other types of injuries have different definitions and characteristics. Acute injuries occur suddenly and are usually the result of a specific incident, such as a fall or collision. Traumatic injuries are typically severe and arise from an unexpected event that causes immediate damage to tissues. Temporary injuries imply a short-lived condition, which does not align with the persistent and long-lasting nature of chronic injuries. Thus, understanding the characteristics of each type helps clarify why "chronic" is the appropriate answer for this question.