Final answer:
For a stack of size 5 with array-based implementation starting at index 0, the stack's top value will be 4 when it is full, as it represents the last element's index.
Step-by-step explanation:
The question involves a concept from data structures in computer science, specifically related to the stack. When a stack has a size limit (referred to as STACK_SIZE), the value of top traditionally represents the index of the last element that was inserted (pushed) into the stack. Since stacks are often implemented with array-based storage starting at index 0, for a stack of size 5, the indexes will range from 0 to 4. Therefore, when the stack is full (i.e., contains 5 elements), the top will point to index 4. Thus, the correct answer to what the value of top will be if a stack of size 5 is full is (c) 4.