Final answer:
If exactly one person gets out after A but before B, it can be written as A - P - B.
Step-by-step explanation:
In this scenario, if exactly one person gets out after A but before B, we can represent it as:
A - P - B
Here, the person labeled as P gets out after A, but before B. The dashes represent the remaining people in the sequence. By using this notation, we can clearly indicate that one person gets out between A and B.