Paul, age $37,$ participates in a Section $401(k)$ plan which allows employees to contribute up to $15$ percent of their salary. His annual salary is $$125,000$ in $2022.$ What is the maximum he can contribute, on a tax$-$deferred basis under a salary reduction agreement, to this plan?

a$.$ $$18,500$

b$.$ $$24,000$

c$.$ $$18,750$

d$.$ $$20,500$

e$.$ None of these choices are correct.