In sailing terminology, what is meant by 'sheets'?

In sailing terminology, 'sheets' refer to the lines or ropes that control the angle of the sails in relation to the wind. They are essential for adjusting the sails to optimize the boat's speed and direction. By pulling or releasing the sheets, sailors can trim the sails to catch the wind effectively, allowing the vessel to sail at an angle that maximizes performance.

The other choices do not accurately define 'sheets.' Weights attached to sails would generally be referred to as "ballast" or "weights," rather than "sheets." Lines used to transport passengers are usually referred to as "handrails" or "lines," rather than anything specific to sail control. Lastly, measurement markings on a sail are not connected to the concept of 'sheets'; instead, they may be considered indicators for adjusting sail trim or for informational purposes but are not inherently related to the act of managing the sails in relation to the wind.