Question

what are pneumatic tools powered by? select the best option. compressed air sand liquid human power

Explanation:

Pneumatic tools are powered by compressed air. This is a fundamental characteristic of pneumatic systems. Compressed air is stored in a tank and then released to drive the tool's mechanism. Sand is not a power source for tools in this context. Liquid is used in hydraulic systems, not pneumatic ones. Human power is manual and not related to the pneumatic principle.

Answer:

Compressed Air