Which of the following is true regarding spare lithium batteries?

Spare lithium batteries are subject to specific regulations due to their potential hazards, particularly the risk of thermal runaway, which can lead to fires. Transportation guidelines for these batteries require that they be carried in carry-on baggage rather than checked baggage. This is because, in the event of a malfunction or overheating, having the batteries accessible in the cabin allows for immediate action to be taken by crew members, whereas checked baggage is not easily accessible once stowed.

Carrying spare lithium batteries in carry-on baggage also aligns with safety measures aimed at minimizing the risks posed by these devices during flight. These guidelines are part of broader aviation safety protocols designed to protect all passengers and crew on board.