【单选题】According to ancient records, natural magnets were employed in China as direction-finding devices. This led to the first compass, called ( ) during the Warring States Period.
【单选题】According to ancient records, natural magnets were employed in China as direction-finding devices. This led to the first compass, called ( ) during the Warring States Period.
【单选题】According to ancient records, natural magnets were employed in China as direction-finding devices. This led to the first compass, called ____during the Warring States Period.