Which of the problems listed will occur if a lead-acid battery is allowed to remain in a discharged condition for a long period of time?

Correct Answer: Option A — The battery may be unable to accept a full charge.

Prolonged discharge leads to the formation of hard lead sulfate crystals on the plates. This sulfation process is often irreversible if left for an extended period, significantly reducing the battery's capacity and preventing it from accepting a full charge, effectively shortening the operational lifespan of the unit.