What safety feature is typically integrated into high pressure boiler systems?

High-pressure boiler systems are designed with multiple safety features to ensure the safe operation of the boiler and to prevent potential accidents or failures. The inclusion of manual reset switches, automatic shutoff valves, and audible alarms all contributes to a comprehensive safety protocol.

Manual reset switches are critical for allowing operators to reinitiate the system only after a fault has been addressed, thus ensuring that any underlying issues are resolved before normal operation resumes. This prevents the boiler from being inadvertently restarted in a potentially unsafe condition.

Automatic shutoff valves are engineered to close in response to specific operational faults or detected anomalies. This feature can help prevent catastrophic failures by isolating the boiler from the system, ensuring that dangerous situations do not escalate.

Audible alarms serve as an alert system for operators, providing immediate notification of potential issues such as pressure fluctuations or other deviations from standard operating parameters. This allows for rapid response to any abnormal conditions, contributing to overall safety.

The integration of all these safety features creates a robust system that enhances the reliability and security of high-pressure boiler operations. Each feature plays a vital role in mitigating risks and ensuring safe functioning, hence making the option "D. All of the above" the correct choice.