Read the stanza from “Paul Revere's Ride.” He said to his friend, "If the British march
By land or sea from the town to-night,
Hang a lantern aloft in the belfry arch
Of the North Church tower as a signal light,--
One if by land, and two if by sea;
And I on the opposite shore will be,
Ready to ride and spread the alarm
Through every Middlesex village and farm,
For the country folk to be up and to arm."

Which best describes the central idea of this stanza?

Paul Revere will warn people that the British are coming as soon as he parts with his friend.
Paul Revere will hang a lamp in a church to let his friend know when the British are coming.
Paul Revere’s friend will send a secret signal to inform him of the British army’s plan.
Paul Revere’s friend will ride through the country alerting everyone that the British army is on the move.