Which structures heal slowly due to poor blood supply?

The correct choice highlights ligaments and capsules as structures that tend to heal slowly due to their limited blood supply. Ligaments, which connect bones to other bones, and joint capsules, which envelop joints, are composed of dense connective tissue that is relatively avascular. This means they do not receive as much blood flow compared to other tissues, which slows down the healing process when they are injured.

Due to their reduced vascularity, healing in these structures can take longer because blood supply is critical for delivering essential nutrients, oxygen, and cells needed for tissue repair. In contrast, tissues with better blood supply, such as muscles and tendons, often heal more quickly.

It's important to understand the specific biology of each type of tissue, as the rate of healing can significantly impact rehabilitation strategies and recovery times in athletic training and rehabilitation contexts.