Final answer:
While none of the provided options directly answer the meaning of 'shift the rudder', option c accurately describes a situation where a ship is moving forward, decelerates, and then continues to slow down with less deceleration.
Step-by-step explanation:
The phrase "shift the rudder" in the context of nautical navigation would generally mean to change the position of the rudder. However, the options presented as possible answers do not explicitly match the standard nautical commands or terminology associated with the rudder's position. Since none of the options provided (a, b, c, d) match the meaning of 'shift the rudder', let's address a related concept.
When considering the acceleration of a ship, option c from the provided information best describes the motion based on the graph. It indicates that the ship is moving forward at a steady rate, then it begins to decelerate in the same direction, and finally, it continues to slow down with less deceleration. This would reflect a change in speed without a change in the direction of travel.
Discussing historical ship design, the introduction of the caravel marked a significant improvement in sea travel due to its larger hulls, which allowed for longer voyages by carrying more provisions. The positioning of the rudder at the rear of the ship enhanced maneuverability, and the use of a lateen sail enabled sailing into the wind, a technique known as 'tacking'.