Consider the Following Script

Consider the following script. What is wrong with the following code
< script type = "text/javascript" >
Var firstNumber;
ThirdNumber;
FirstNumber = window.prompt("Enter an integer", "0") ;
SecondNumber = window.prompt("Enter an integer", "0") ;
ThirdNumber = firstNumber + secondNumber;
< /script >

A) thirdNumber in line 7 must be in quotes.
B) The words Enter an integer in line 6 should not be in quotes.
C) The word thirdnumber in line 3 should have a comma after it.
D) The word var must be placed before thirdNumber in line 3.