The purpose of a cylindrical roller bearing is to:

The purpose of a cylindrical roller bearing is to contain radial motion of the shaft, which makes the choice of answer C appropriate. These bearings are specifically designed to support loads that act perpendicular to the axis of the shaft. The cylindrical shape of the rollers allows for greater surface contact with the races compared to other bearing types, facilitating the effective transmission of radial loads while accommodating minimal axial load capabilities.

Understanding this role in bearing design is critical when considering their application in machinery, where they help ensure smooth and efficient operation under varying load conditions. In contrast, other options—such as containing axial motion or limiting rotational speeds—do not align with the primary function of cylindrical roller bearings, as these are typically more suited for other types of bearings. Similarly, while friction reduction is an important aspect of many bearing types, the design and operational role of cylindrical roller bearings are specifically focused on managing radial loads.