| Referring to the device shown in the illustration, the coiled sensing lines "A" and "B", are used simultaneously when the pilot is used __________ . |
| A) to maintain a level in a tank vented to the atmosphere, pressurized, or operating under a vacuum |
| B) to maintain a tank level where there exists a variable vapor pressure atmosphere |
| C) as a square root extractor when variable ratios are present in the processing system |
| D) to maintain a constant flow differential across a turbine- driven, centrifugal pump |
