Question

question: 2 which one of these is not a command that karel knows? turn left turn right move forward put down a ball

Explanation:

In Karel programming, 'Turn Left', 'Turn Right', 'Move Forward', and 'Put Down a Ball' are standard commands.

Answer:

None of the above (assuming all are valid commands for Karel in typical contexts. If there is a specific context - not provided - where one is incorrect, more information is needed. But based on general knowledge of Karel the Robot programming environment, all of these are common commands).