How do you check if Karel is next to a beeper before picking it up?

The choice where the code checks if Karel is next to a beeper before picking it up is correct because it uses the appropriate method to verify Karel's position relative to the beeper. The function nextToABeeper() is called to determine if there is a beeper adjacent to Karel, and if the condition evaluates to true, the pickBeeper() command is executed. This ensures that Karel will only attempt to pick up a beeper if there is one available right next to it, preventing errors or unexpected behavior in the program.

This approach demonstrates a fundamental programming principle: checking conditions before executing actions based on those conditions. This helps maintain the logical flow of the program and ensures that actions are executed safely and effectively. The other options either involve incorrect actions or do not check the condition necessary for picking up the beeper, leading to improper outcomes in the program.