Which of the following is NOT a common type of helmet?

The statement regarding one-half helmets being not a common type is accurate because one-half helmets, often referred to as half helmets or "skull caps," offer minimal coverage and protection compared to other types. While they are available and used by some riders, they are less common as safety standards have shifted towards designs that offer better protection to the rider's head, face, and chin.

Full face helmets provide comprehensive coverage, protecting the entire head including the chin and face. Three-quarters helmets cover the head and ears but leave the face exposed, striking a balance between protection and visibility. Modular helmets, also known as convertible helmets, provide the advantages of both full face and open face designs, as they have a hinged chin bar that can be lifted while still offering the safety benefits of a full face helmet when closed. These types are more prevalent on the market due to their extensive protective features and advancements in safe riding practices.