Object modules generated by assemblers that contain unresolved external references are resolved for two or more object modules by a/an A. operating system B. loader C. linker D. compiler E. None of the above

The correct answer is C. linker.

An object module is a file that contains machine code for a single function

or subroutine. It is created by an assembler, which translates assembly language into machine code. An object module may contain unresolved external references, which are references to functions or data that are defined in other object modules.

A linker is a program that combines multiple object modules into a single executable file. It resolves all unresolved external references by finding the corresponding

definitions in other object modules. The linker also performs other tasks, such as adding relocation information and symbol tables.

The operating system is responsible for loading executable files into memory and running them. It does not resolve external references.

The loader is a program that loads executable files into memory. It does not resolve external references.

The compiler is a program that translates source code into machine code. It does not resolve external references.

Therefore, the correct answer is C. linker.