Which of the following states one of Williston's Rules regarding the parol evidence rule?

Question 7 options:

A)

Ascertaining the actual intent of the parties is critical.

B)

The use of "course of dealing" or "usage of trade" will supply missing or disputed terms.

C)

The presence of a merger clause creates a rebuttable presumption that an integration is total.

D)

If an instrument appears to be complete on its face, the instrument is conclusively presumed to be a total integration.