Aresearcher shows a baby a toy. together they bury the toy in some sand in one location in the sandbox. than the researcher reaches into the sand in another location in the sandbox and pulls out the toy. what is this type of paradigm called

This type of paradigm is called violation of expectations .

Explanation:

What does violation of expectations mean?

Violation expectation is a method which is used to teach and test if children understand that a solid object can not shift from one place to a place that is already occupied by another solid object.

If children show signs of being surprised by the fact that an object moved and occupied a space that was previously occupied that means they have an understanding.

i would say b. research typically uses a variety of sources