Final answer:
Fractures can be classified as open or closed, where an open fracture involves a wound through the skin and a closed fracture does not break the skin.
Step-by-step explanation:
Form closure in the context of the given choices seems to relate to fractures, which can be classified in various ways depending on their features. The two categories of fractures that can form closures are open and closed. An open fracture occurs when the bone breaks and pierces the skin, creating an open wound, whereas a closed fracture refers to a bone break that does not disrupt the skin.