"if radiometric evidence proves that a rock layer contains a fossil that is approximately 10,000 years old, what can also be determined using the principle of superposition? "

If the layer is 10,000 years old (radiocarbon dating goes back about 40,000 yrs) as determined by radiometric dating, then the rock layers or strata above it should be younger and the strata below should be older. This is provided that the rocks have not been deformed as in an overturned syncline. Careful geological mapping could determine if they were overturned or not.

Iwould say d. eye contact and body language because you aren’t using any spoken communication. hope this : )