Layout guidance

I have a section of a site I am about to develop in asp.net core 2.0 that has about 5 options to configure before a form can be submitted. The options are consecutive in that the first one constrains the choices for the subsequent one etc.

This brings me to the decision, does it make sense to start all selects unconstrained in order to allow a user to start anywhere in the chain? For example. if the third options is chosen first, the remaining options trim to account if necessary? Or blank all but the first and populate the next select consecutively as the user progresses?

Lastly, what type of page design would be considered most optimal for the user, I think page reloads after each choice (worse even is a discrete page per choice) would be very old school.

What are the opinions from more experienced persons?

Thanks!