What type of error occurs during the process of linking a program?

During the process of linking a program, a linker error occurs when the linker is unable to combine the various object files into a final executable program. This type of error typically arises when there are unresolved external references, such as functions or variables that are declared but not defined, or when there are conflicts between multiple definitions of the same function or variable across different files. The linker cannot proceed with creating the executable because it needs all declared references to be resolved, ensuring that the code can call those functions or access those variables at runtime.

Linker errors fundamentally differ from syntax errors, which are related to improper use of the programming language's syntax during compilation, and runtime errors, which happen when a program is executed and encounters problems like accessing invalid memory or division by zero. Additionally, semantic errors occur when the code runs without execution but produces incorrect results due to logical issues in the code structure. Thus, the nature of linker errors is specific to the linking stage, making it the correct choice in this context.