Option 1: Hydrochloric Acid -> A strong acid used in industrial processes and cleaning, not in batteries.
Option 2: Boric Acid -> A weak acid commonly used as an antiseptic and insecticide, not suitable for battery applications.
Option 3: Carbonic Acid -> A weak acid formed when carbon dioxide dissolves in water, not used in batteries.
Option 4: Sulphuric Acid -> The electrolyte used in lead-acid batteries, typically in diluted form (approximately 30-50% concentration).
Hence, Option 4: Sulphuric Acid -> Lead-acid car batteries use diluted sulphuric acid as the electrolyte which reacts with lead plates to produce electrical energy through electrochemical reactions -> correct