Walter worked nights as a clerk in a fast$-$food store. On his last work shift, Walter's boss told him, $"$I$\text{'}$m really grateful for the year that you have worked here. I am going to give you a bonus of $$1,000$ in your last paycheck, but I need you to cover Johnny$$s shift for me and stay a little later." In response, Walter stayed later and covered Johnny$$s shift. When Walter got his last paycheck, there was no bonus. If Walter sues, the likely result will be:

Group of answer choices

Walter will win, as the promise is enforceable.

Walter will lose based upon the preexisting duty rule.

Walter will lose because he can$$t use past acts to satisfy consideration.

Walter will win, as no consideration is required to modify an employment contract.