TLIs are normally used to monitor which of the following critical materials?

The correct answer relates to the monitoring of critical materials that are integral to various industrial and operational processes. TLIs, or Temperature and Level Indicators, are commonly used to monitor materials that require careful regulation and maintenance to ensure optimal performance and safety.

Fuel, lube oil, and water are essential for the operation of machinery and systems within many industries, such as power generation and manufacturing. These materials need to be monitored closely for temperature and level to prevent overheating, ensure proper lubrication, and maintain adequate water levels for cooling systems.

The other choices, while they do encompass materials that might be monitored in different contexts, do not align with the typical use of TLIs as focused on critical operational inputs like fuel and lubricants that require stringent monitoring to maintain system integrity and efficiency.