Which command would you use to move Karel forward one step?

The command that successfully moves Karel forward one step is "move()". This command is specifically designed for Karel's programming language, allowing the robot to take a single step in the direction it is facing.

Utilizing this command correctly engages Karel's movement functionality, enabling effective navigation across the grid or environment it operates in. This concept is fundamental in programming with Karel, as movement commands form the basis of task execution, such as reaching specified locations or interacting with objects.

Other options like "stepForward()", "go()", and "advance()" do not correspond with standard commands in Karel's programming environment, which is why they would not yield the desired action of moving Karel forward.