| Which of the following statements is true concerning pressure limit switches and pressuretrols installed on auxiliary boilers? |
| A) They are bimetallic elements sensing temperature differentials corresponding to pressure changes. |
| B) They consist of a bellows assembly, linked with a snap action switch, through a pressure adjusting mechanism. |
| C) They automatically relieve excessive steam pressure by acting as a pilot to the safety valve. |
| D) They automatically restart the burner sequence via the high water level signal. |
