The answer is B. Gear.
A scissors is a tool that consists of two blades pivoted so that the sharpened edges slide against each other when the handles opposite to the pivot are closed. The blades are typically used to cut paper, cloth, rope, or other thin materials.
A lever is a simple machine that consists of a beam or rod that pivots on a fulcrum. When a force is
applied to one end of the lever, it causes the other end to move in the opposite direction. Levers are used to amplify force, to change the direction of a force, or to move objects over a distance.A toothed wheel is a wheel with teeth around its edge. The teeth are typically used to mesh with the teeth of another toothed wheel, or with a rack. Toothed wheels are used to transmit power, to change the direction of motion, or to change the speed of motion.
A wedge is a simple machine that consists of a thin piece of material with one thick end and one thin end. The wedge is used to split or separate objects by applying force to the thick end.
A press is a machine that is used to apply force to an object. Presses are used to perform a variety of tasks, such as printing,
stamping, and forging.A pulley is a simple machine that consists of a grooved wheel with a rope or cable that runs through it. The pulley is used to change the direction of a force, or to lift heavy objects.
In the pair “scissors : lever”, the scissors are a type of lever. The blades of the scissors are the lever arms, and the pivot point is the fulcrum. When the handles of the scissors are closed, the blades move towards each other, which cuts the material between them.
In the pair “toothed wheel : gear”, the toothed wheel is a type of gear. The teeth of the toothed wheel mesh with the teeth of another toothed wheel, or with a rack. This allows the toothed wheel to transmit power, to change the direction of motion, or to change the speed of motion.
Therefore, the answer is B. Gear.