The following C code is vulnerable to a buffer overflow attack because it calls gets$().$ Select options in the following sketch of the stack to show the stack frame of the procedure option. Note: The size of

each block of memory in the stack is to be indicated in bytes $-$ the diagram does not indicate the size of each block.

How many characters is the longest input line that can be typed without overwriting the return address on the stack?

$x$ bytes

long option $()\{$

char input$[16]$;

gets$($input$)$;

return input$[6]==\text{'}$y$\text{'}$;

$\}$

The assembly code generated by the compiler is as follows.

option: $($in the picture$)$

Q$.$ How many characters is the longest input line that can be typed without overwriting the return address on the stack? The answer is not $24,16$ or $0.$ What can be the right answer?