Final answer:
The Haversian canal, located in compact bone, contains blood vessels and nerve fibers, and is central to the osteon, the structural unit of compact bone.
Step-by-step explanation:
The Haversian canal, also known as the central canal, is a fundamental feature of the microscopic structural unit of compact bone, called an osteon or Haversian system. Each osteon consists of concentric rings of calcified matrix known as lamellae. Running down the center of each osteon is the Haversian canal, which contains blood vessels, nerve fibers, and lymphatic vessels. These vessels and nerves can branch off through perpendicular channels known as Volkmann's canals, connecting to the periosteum and endosteum. Therefore, the correct answer to the student's question is:
(a) Contains blood vessels and nerves