COTS product reuse means
(a) Class and function libraries that implement commonly used abstractions are available for reuse
(b) Shared components are woven into an application at different places when the program is compiled
(c) Large-scale systems that encapsulate generic business functionality and rules are configured for an organization
(d) Systems are developed by configuring and integrating existing application systems
I had been asked this question during an interview.
Question is taken from Software Reuse topic in portion Advanced Software Engineering of Software Engineering