Final answer:
An aquitard is the most accurate term for a well-sorted layer of rock, like shale or clay, that does not allow water to move through it. A permeable layer would be a rock that is well sorted and allows water to flow through it.
Step-by-step explanation:
The most accurate term for a layer of rock like shale or clay that is well sorted but does not allow water to move through it is aquitard (option c).
An aquitard is a geologic unit that restricts or slows the flow of groundwater due to its low permeability. Shale and clay are examples of sedimentary rocks that can act as aquitards. On the other hand, a rock that is well sorted and allows water to move through it would be called a permeable layer (option d).