Program binaries in many systems are typically structured as follows. Code is stored starting with a small, fixed virtual address, such as $0$. The code segment is followed by the data segment that is used for storing the program variables. When the program starts executing, the stack is allocated at the other end of the virtual address space and is allowed to grow toward lower virtual addresses. What is the significance of this structure for the following schemes ?
$a$. Contiguous memory allocation
$b$. Pure segmentation
$c$. Pure paging
