Final answer:
Buffer overflows are categorized into stack overflow and heap overflow, with the correct answer being 'stack overflow'. Stack overflows occur when there's too much memory used on the call stack, while heap overflows concern the heap memory. Other listed options are different types of security vulnerabilities, not buffer overflow categories.
Step-by-step explanation:
Buffer overflows can be divided into two categories: stack overflow and heap overflow. Option a) Stack overflow is the correct answer. A stack overflow occurs when too much memory is used on the call stack which is the limited amount of space allocated for functions, local variables, and control flow. Once the stack's capacity is breached, it results in a buffer overflow condition where the excess data can overwrite adjacent memory locations.
Heap overflows occur when the buffer overflow is in the heap section of memory, which is dynamically allocated during runtime for variables that are not allocated on the stack. Unlike stack overflows, heap overflows are exploited differently, as they tend to overwrite program data instead of the call stack.
Options b) Code injection, c) Integer overflow, and d) Format string vulnerability are all different security vulnerabilities that can be exploited in various situations but are not categories of buffer overflows.