1. Single Component Analysis: Many gas analyzers are dedicated to a single task, such as measuring the concentration of oxygen ($O_2$) in a boiler flue to optimize combustion or monitoring carbon monoxide ($CO$) levels for safety in a parking garage.
2. Multi-Component Analysis: Advanced gas analyzers, such as those based on Infrared (IR) spectroscopy or Gas Chromatography (GC), are capable of identifying and quantifying multiple different gases simultaneously from a single sample stream. For example, an emissions analyzer might measure $CO$, $CO_2$, $NO_x$, and $SO_2$ at the same time.
3. Summary: The technology is versatile; depending on the sensor type and software, a gas analyzer can be used for either
single or multi-component analysis. Therefore, option 3 is the most comprehensive and correct choice.