Answer:
The answer is "that involves the scientific process of how our brains comprehend three-dimensional imagery".
Explanation:
A restrictive clause is a relative clause that provides essential information about a noun or noun phrase, limiting it. It can also be called defining relative clause. A restrictive clause is not set off by commas.
In the structure "Because," Mr. Dodson replied, "it's a movie, made by some of the greatest animators in the business, that involves the scientific process of how our brains comprehend three-dimensional imagery" we can easily find the restrictive clause. We have two sentences modifying the noun "movies", offering information about it. However, the clause "made by some of the greatest animator in the business" is set off by commas, so it cannot be the restrictive clause we are looking for.
On the other hand, "that involves the scientific process of how our brains comprehend three-dimensional imagery" modifies the noun "movies" by limiting it - it is not any movie, it's a specific one -, and is not set off by commas. Therefore, it is the restrictive clause we are looking for.
