Final answer:
The correct verb form to complete the command is "ten".
Step-by-step explanation:
The correct verb form to complete the command "cuidado con el fuego!" is Ten.
This command is telling someone to be careful with fire, so the proper form of the verb is the second person singular, which is ten.
For example, you can say "Ten cuidado con el fuego" which means "Be careful with the fire."
Learn more about Spanish verb forms