You should fill out one DS-160 visa application form and pay one visa charge keeping in
mind the end goal to schedule an appointment for your C1D visa. At the time of interview, you can
ask for that the Officer likewise consider your application for a B1/B2 visa. If approved, you won't
have to pay an extra charge. It would be ideal if you take note of that this double visa course of
action exists for C1D and B1/B2 visas, not for other visa combinations.