Question

when splinting an injured body part, you should—
use a rigid splint for all injured body parts.
support the injured part in the position you find it.
all of the above
keep the injured part as straight as possible

Explanation:

When splinting, you should support the injured part in the position you find it (unless it's an extreme situation like blocking circulation). Rigid splints aren't for all (e.g., some hand injuries might use a softer or custom - made splint). Keeping it as straight as possible is not always correct as you don't want to force a position.

Answer:

Support the injured part in the position you find it.