Answer: Alignment
Step-by-step explanation:
The principle of repitition indicates that some aspect of a design are repeated. This can be in form of bullet list, lines, color etc.
Balance has to do with how the weight is distributed.
The Principle of Alignment means that the pictures on a page should be connected visually to another thing.
Principle of Proximity simoly means that the items that are related on a page should be close to each other.
Therefore, the principles of page layout that Sam is planning to use in this artwork is alignment.