Slow oxidative fibers are suited for endurance-type activities.

Choice A reason: Osteocytes are mature bone cells that maintain bone tissue and communicate with other bone cells. They do not actively resorb bone.

Choice B reason: Osteoblasts are responsible for bone formation, not resorption. They synthesize and secrete the bone matrix and aid in mineralization.

Choice C reason: This is correct. Osteoclasts are large, multinucleated cells that break down bone tissue during the process of bone resorption. They release enzymes and acids that dissolve the bone matrix, playing a critical role in bone remodeling and calcium homeostasis.

Choice D reason: Osteogenic cells are stem-like precursors that differentiate into osteoblasts. They do not directly resorb bone but contribute to bone formation.

Choice E reason: Stem cells are undifferentiated cells that can give rise to various cell types, including osteogenic cells. However, they are not directly involved in bone resorption.

Choice A reason: Cross bridges are formed between actin and myosin during contraction. T tubules do not hold them in place; their role is electrical, not structural.

Choice B reason: While T tubules are embedded in the muscle fiber, their function is not to provide structural support. That role is fulfilled by connective tissues like endomysium and cytoskeletal proteins.

Choice C reason: G and F actin are stabilized by proteins like tropomyosin and nebulin, not T tubules. T tubules are involved in electrical signaling.

Choice D reason: This is the correct answer. T tubules are invaginations of the sarcolemma that conduct action potentials deep into the muscle fiber. This ensures that the signal for contraction reaches all parts of the muscle simultaneously, triggering calcium release from the sarcoplasmic reticulum.

Choice E reason: Glucose synthesis occurs in the liver and other tissues via gluconeogenesis. Muscle cells use glucose for energy but do not synthesize it through T tubules.