There are several components to a functional osteon. changes to which of the following components would make the bones less strong overall and cause the bones to bend under a person's body weight?

The osteon is the fundamental functional unit of compact bone and it consists of concentric layers (lamellae), of compact bone tissue that surrounds a central canal. What gives a strength, hardness and rigidity to bone is the presence of mineral salt in the osteoid matrix, a complex of calcium and phosphate - hydroxyapatite. Calcified bone contains about 25% organic matrix (2-5% of which are cells), 5% water and 70% inorganic mineral (hydroxyapatite). So, changes in hydroxyapatite would cause the bones to bend under a person's body weight.

Hydroxyapatite is your answer. It is a mineral form of calcium which is great for your bones and changes in it would cause the bones to bend under a person's body weight.