Which of the following instruments provides information about battery charge level?

The instrument that provides information about battery charge level is the ammeter. An ammeter measures the flow of electric current in a circuit, indicating whether the battery is charging or discharging. When the aircraft's engine is running and the alternator is functioning properly, the ammeter will show a positive reading, indicating that the battery is being charged. Conversely, if the ammeter shows a negative reading, it indicates that the battery is discharging, alerting the crew to potential electrical issues.

In contrast, the exhaust gas temperature gauge measures the temperature of the engine's exhaust gases, which is crucial for monitoring engine performance but does not provide information about the battery's charge. The engine oil pressure gauge indicates the pressure of the oil circulating within the engine, essential for ensuring adequate lubrication, but it does not relate to electrical systems. The manifold pressure gauge measures the pressure within the engine's intake manifold, providing data important for engine performance and fuel-air mixture but failing to indicate battery status. Thus, the ammeter is the correct choice for monitoring battery charge level.