Answer: C
Both A and B are correct
Step-by-step explanation:
Latent heat is the hidden heat.
Latent heat is the heat energy required to change one state of matter to another state of matter without change in temperature. For example, solid state to liquid state, or liquid state to gaseous state.
Thermometer can not detect the latent heat. That is why it is called hidden heat.
If Technician A says that latent heat is hidden heat and cannot be measured on a thermometer. And Technician B says that latent heat is hidden heat that is required for a change of state of matter, then we can therefore conclude that both Technician A and Technician B are correct.