Consider the following code and indicate which of the following

Consider the following code and indicate which of the following is a correct explanation what is happening in the code:

#include

#include

int main$()$

$\{$

std::stack stackClass;

stackClass.push$("$John$")$;

stackClass.push$("$Peter$")$;

stackClass.pop$()$;

std:: string num $="5"$;

stackClass.push$($num$)$;

stackClass.push$("$Mary$")$;

stackClass.push$("$Fred$")$;

stackClass.pop$()$;

stackClass.push$("$Ben$")$;

return $0$;

$\}$

a$.$ STEP STACK CONTENTS ACTION EXPLANATION

$1$ Initialization stackClass is initially an empty stack.

$2$ "John" stackClass.push$("$John$")$ "John" is pushed onto the stack.

$3$ "John", "Peter" stackClass.push$("$Peter$")$ "Peter" is pushed onto the stack.

$4$ "John" stackClass.pop$()$ The top element $("$Peter$")$ is popped from the stack.

$5$ "John" std::string num $="5"$ A new string $"5"$ is created.

$6$ "John","$5"$ stackClass.push$($num$)"5"$ is pushed onto the stack.

$7$ "John", $"5",$"Mary" stackClass.push$("$Mary$")$ "Mary" is pushed onto the stack.

$8$ "John", $"5",$ "Mary","Fred" stackClass.push$("$Fred$")$ "Fred" is pushed onto the stack.

$9$ "John", $"5",$ "Mary" stackClass.pop$()$ The top element $("$Fred$")$ is popped from the stack.

$10$ "John", $"5",$ "Mary","Ben" stackClass.push$("$Ben$")$ "Ben" is pushed onto the stack.

At the end of these steps, the stack contains the elements "John," $"5,"$ "Mary," and "Ben," with "Ben" being the top element.

b$.$ STEP STACK CONTENTS ACTION EXPLANATION

$1$ Initialization stackClass is initially an empty stack.

$2$ "John" stackClass.push$("$John$")$ "John" is pushed onto the stack.

$3$ "Peter","John" stackClass.push$("$Peter$")$ "Peter" is pushed onto the stack.

$4$ "Peter" stackClass.pop$()$ The top element $("$John$")$ is popped from the stack.

$5$ "John" std::string num $="5"$ A new string $"5"$ is created.

$6"5",$ "Peter" stackClass.push$($num$)"5"$ is pushed onto the stack.

$7$ "Mary","$5",$ "Peter" stackClass.push$("$Mary$")$ "Mary" is pushed onto the stack.

$8$ "Fred","Mary","$5",$ "Peter" stackClass.push$("$Fred$")$ "Fred" is pushed onto the stack.

$9$ "Fred","Mary","$5"$ stackClass.pop$()$ The top element $("$Peter$")$ is popped from the stack.

$10$ "Ben","Fred","Mary","$5"$ stackClass.push$("$Ben$")$ "Ben" is pushed onto the stack.

At the end of these steps, the stack contains the elements "Ben", "Fred","Mary", $"5"$ with $"5"$ being the top element.

c$.$ STEP STACK CONTENTS ACTION EXPLANATION

$1$ Initialization stackClass is initially an empty stack.

$2$ "John" stackClass.push$("$John$")$ "John" is pushed onto the stack.

$3$ "John", "Peter" stackClass.push$("$Peter$")$ "Peter" is pushed onto the stack.

$4$ "John" stackClass.pop$()$ The top element $("$Peter$")$ is popped from the stack.

$5$ "John" std::string num $="5"$ A new string $"5"$ is created.

$6$ stackClass.push$($num$)"5"$ is pushed onto the stack.

An error will occur at this point, as it is not possible to push a numeric value onto a stack with string values.

d$.$

STEP STACK CONTENTS ACTION EXPLANATION

$1$ Initialization stackClass is initially an empty stack.

$2$ "John" stackClass.push$("$John$")$ "John" is pushed onto the stack.

$3$ "Peter","John" stackClass.push$("$Peter$")$ "Peter" is pushed onto the stack.

$4$ "Peter" stackClass.pop$()$ The top element $("$John$")$ is popped from the stack.

$5$ "Peter" std::string num $="5"$ A new string $"5"$ is created.

$6$ stackClass.push$($num$)"5"$ is pushed onto the stack.

An error will occur at this point, as it is not possible to push a numeric value onto a stack with string values.