Question

comparing systems
what do heating systems, cooling systems, and heat engines have in common?
they deactivate thermal energy.
they create thermal energy.
they destroy thermal energy.
they transfer thermal energy.

Explanation:

Heating systems transfer thermal energy to warm a space. Cooling systems transfer thermal energy out of a space to cool it. Heat engines transfer thermal energy to do work. According to the law of conservation of energy, energy cannot be created or destroyed. So options that say create or destroy thermal energy are wrong. And there's no such thing as deactivating thermal energy in this context.

Answer:

They transfer thermal energy.