By default, JavaScript allows us to write to an undeclared variable (it declares it implicitly for us). If we want the interpreter to treat such a situation as an error, we have to:

To treat writing to an undeclared variable as an error in JavaScript, you would need to place the "use strict"; directive at the beginning of the script.

So the correct option is:

place the "use strict"; directive at the beginning of the script.

By using the "use strict"; directive, you enable strict mode in JavaScript, which helps catch common mistakes and enforces stricter rules for variable declaration and usage. It will treat writing to an undeclared variable as an error instead of implicitly declaring it.