Uber and lyft customers often complain about the practice of ""surge"" or ""prime-time"" pricing used by these companies during periods of peak demand. this is an example of a pricing policy.

The correct word for the blank space is:  dynamic.

Explanation:

Dynamic pricing policies are based on certain time frames in which the demand for a service is requested. According to those time frames, the time could be cheaper or more expensive. Businesses are said to establish flexible prices under this scenario.

On apex it is A flat taxation