____________ is a common type of gear.

• A. Spur
• B. Helical
• C. Bevel
• D. All of the above are common types of gears.

Answer: (D)

Gears come in several common families, each serving different needs in mechanical transmissions. Spur gears with straight teeth are the simplest and most widely used for transferring motion between parallel shafts. Helical gears, with angled teeth, run more smoothly and quietly and can handle higher loads. Bevel gears are designed to connect shafts that intersect or meet at an angle, changing the direction of drive. Because all three forms are routinely found in machinery, the option stating that all of the above are common types accurately reflects how gear systems are designed in real-world applications.