Final answer:
The base study shows the base flood discharge and frequency.
Step-by-step explanation:
The correct answer is b) Discharge, frequency.
Discharge refers to the volume of water flowing through a river or stream at a given point. It is usually measured in cubic feet per second (cfs) or cubic meters per second (cms).
Frequency, in the context of flood events, refers to how often a certain magnitude of flood occurs in a given timeframe. It is commonly expressed as a recurrence interval, which represents the average time between floods of a certain magnitude occurring.