A _____ is used to sense temperature from a distant location.

A remote bulb is designed specifically to sense temperature at a distance from the measuring device. It operates by having a bulb that contains a thermometric liquid, which expands and contracts in response to temperature changes. This bulb is typically connected to a capillary tube that transmits the temperature changes back to the measurement instrument. The advantage of using a remote bulb is that it allows for temperature sensing in environments that may be hazardous or difficult to access, while still providing accurate readings.

The other options, while related to temperature measurement, do not serve this specific function as effectively. An insertion bulb is generally used for direct contact temperature measurement within pipes or reactors, an immersion sensor is designed to be fully submerged in a fluid for temperature readings, and a capillary tube, while essential for transmitting the temperature signal, does not sense temperature itself. Thus, the remote bulb clearly fulfills the requirement for distant temperature sensing, making it the most suitable choice in this context.