The rings of matrix within an osteon are called:

A. forms the parietal and frontal bones
These bones are formed by intramembranous ossification, not endochondral. Intramembranous ossification occurs directly from mesenchyme.

B. results when the mesenchyme condenses into a fibrous CT around brain
This describes intramembranous ossification, not endochondral. Endochondral ossification uses a cartilage model, not fibrous connective tissue.

C. occurs when bones develop from cartilage models
Endochondral ossification is the process by which long bones and most bones of the body are formed by replacing a hyaline cartilage model with bone.

D. occurs when multiple centers of ossification converge together
While multiple ossification centers do form during endochondral ossification (e.g., primary in diaphysis, secondary in epiphyses), this does not define the process-it’s development from a cartilage model that is essential.

A. sweat glands releasing fluid
Sweat helps with cooling through evaporation, not facial flushing.

B. constriction of the blood vessels in the dermis of my skin
Vasoconstriction reduces blood flow to the skin and is a response to cold, not exercise.

C. dilation of the blood vessels in the dermis of my skin
Vasodilation increases blood flow to the skin surface, releasing excess heat and resulting in a flushed appearance after physical exertion.

D. sebaceous glands releasing their product
Sebaceous glands produce oil (sebum) for waterproofing the skin and are unrelated to thermoregulation.

E. dilation of the blood vessels in the epidermis of my skin
The epidermis is avascular (has no blood vessels). Dilation occurs in the dermis.