The parent of a child with osteomyelitis asks why his child is in so much pain. What will the nurse respond causes the pain experienced with osteomyelitis?

A. Circulatory congestion of the skin does not directly cause the intense, deep pain associated with osteomyelitis. B. Osteomyelitis is an infection of the bone, often involving the bone marrow. The buildup of purulent material increases pressure within the rigid bone structure, causing severe pain. C. While casts can cause discomfort if improperly applied, the primary source of pain in osteomyelitis is the infection itself. D. Inelastic bone structure may contribute to pressure buildup, but this is secondary to the infection in the bone marrow, which is the direct cause of pain.