What are the signs of a failing lead-acid vs AGM battery in emergency vehicles, and how should they be tested?

• A. Lead-acid shows fast cranking and low self-discharge; AGM maintains voltage under load; test with a simple voltmeter.
• B. Lead-acid is silent; AGM makes a buzzing sound.
• C. Lead-acid shows slow cranking and higher self-discharge; AGM maintains higher voltage longer but declines under load; test with a load test and check internal resistance.
• D. Lead-acid and AGM behave identically in all tests.

Answer: (C)