Bearing types composed of rollers arranged between two races are known as what?

The correct answer is "Rolling-element." Bearings that have rollers arranged between two races are designed to facilitate smooth rotational movement and support radial and axial loads. The rollers reduce the area of contact and friction between the bearing components, as compared to plain bearings which operate on a sliding friction principle.

Rolling-element bearings are categorized based on the shape of the rolling elements, which can include balls or cylindrical rollers, and they are essential in various applications, from machinery to automotive systems, because they allow for efficient movement and load handling. This design is critical for applications where high speeds and loads are present, as it ensures durability and performance.

The other options do not accurately describe the type of bearing in question. Plain bearings consist of two surfaces sliding against one another without rolling elements and are typically used in situations where low speed and low loads are involved. Outer and inner do not represent specific types of bearings but rather refer to components of various bearing systems.