What is the primary function of proprietary software?

Proprietary software is primarily defined as software that is owned by an individual or a company. The ownership means that users must typically purchase a license to use it, which restricts the software’s use, modification, and distribution by anyone other than the owner. This aligns with the definition of proprietary software as commercial software purchased from a vendor.

In contrast, the other choices refer to different types of software that do not fit the proprietary model. For instance, while cache-related software serves a function related to performance improvement in web browsing, it does not fall into the proprietary category. Similarly, freeware and trial versions offer different models of software distribution that are either free or have limited-time usage without a purchase necessity. Thus, the characterization of proprietary software as a product that requires purchase and licensing is what makes it distinct and aligns with choice B.