what is the most commonly used automotive battery?\nlead acid\ngel\nagm\nlithium

Brief Explanations:

Lead - acid batteries are widely used in automobiles due to their relatively low cost, ability to provide high - current surges for starting the engine, and well - established manufacturing and recycling infrastructure. GEL (gel - electrolyte) and AGM (absorbent glass mat) are types of valve - regulated lead - acid batteries but are more specialized (e.g., AGM is used in some high - performance or vibration - resistant applications). Lithium - ion batteries are becoming more common in electric and hybrid vehicles but are still not as ubiquitous as lead - acid for traditional internal combustion engine vehicles in terms of sheer numbers.

Answer:

Lead Acid