SELECT ALL that are true of the following code:

#include

int userNumber$()$

$\{$

std::cout $<<$ Enter a number: $"$;

int b$\{\}$

std::cin $>>$ b;

return b;

$\}$

int main$()\{$

const int a$\{25\}$;

const int b$\{$userNumber$()\}$;

const int c$\{$a$+$b$\}$;

std::cout $<<$ c $<<\text{'}$

$\text{'}$;

return $0$;

$\}$

a is a compile time constant

b is a compile time constant

It$$s hard to tell if b is a compile$-$time const or a runtime const.

The compiler keeps track of whether a const variable is a runtime or compile$-$time constant.

the first answer choice is correct, but there are two others that are too, which ones are they?