Final answer:
The Principle of Original Horizontality allows you to assume that the beds were tilted after they were deposited.
Step-by-step explanation:
The principle that allows you to assume that the beds were tilted after they were deposited is the Principle of Original Horizontality.
According to this principle, sedimentary layers are originally deposited horizontally. Any tilting or folding of the rock occurs after it is deposited.
For example, if you observe an outcrop of steeply inclined sedimentary layers, it can be inferred that the beds were tilted after they were originally deposited horizontally.