Cells that break down bone tissue are called:

Rationale:
A. This is a sugar component of DNA, not an energy source for muscle contraction.
B. This is a neurotransmitter that stimulates muscle fibers at the neuromuscular junction, initiating contraction. However, it is a signaling molecule, not the direct energy source.
C. These (DNA and RNA) store and transmit genetic information but do not supply energy for muscle contraction.
D. ATP is the immediate and primary energy source for muscle contraction. It provides energy for the cross-bridge cycle between actin and myosin filaments, as well as for pumping calcium back into the sarcoplasmic reticulum during relaxation. Without ATP, muscle contraction and relaxation cannot occur (as seen in rigor mortis).

Rationale:
A. Secretes the lubricating fluid for a synovial joint describes the synovial membrane, not a bursa.
B. Prevents friction between skin and bone, or a muscle tendon and bone; A bursa is a small, fluid-filled sac that cushions and reduces friction between moving structures, such as tendons, muscles, and bones. This helps facilitate smooth movement and prevents tissue damage.
C. Surrounds a tendon at the point where the tendon crosses a joint describes a tendon sheath, which is distinct from a bursa.
D. Is the strong band of connective tissue that holds bones together at a synovial joint refers to a ligament, not a bursa.