Assume Rocky Mountain Railway is considering hiring a reservations agency to handle passenger reservations. The agency would charge a flat fee of $$14,000$ per month, plus $$1$ per passenger reservation. What is the total reservation cost if $50,000$ passengers take the trip next month?

A$.$ $$50,000$

B$.$ $$14,000$

C$.$ $$1\mathrm{.}28$

D$.$ $$64,000$