Based on what you have read, unlicensed plumbers might

The correct answer is B: not know the state law.

Explanation: Unlicensed plumbers may lack the necessary training and knowledge about state laws and regulations governing plumbing work. This can lead to potential legal issues and unsafe practices. While they might have tools and can perform some work, their lack of licensing indicates they may not be aware of the legal requirements in the field. If you have more questions or need further assistance, feel free to ask!