Final answer:
Without specific historical data or a probability distribution chart for flow rates, it is not possible to calculate the probability of a flow event reaching 800 m^3/s in a given year on a stream. The correct answer is option c. Can't deduce from the information on the chart
Step-by-step explanation:
The question pertains to the probability of a flow event reaching 800 m3/s in a given year in a stream. Unfortunately, to accurately calculate this probability, specific data or a probability distribution is needed, which typically comes from historical flow records or statistical models.
As the provided reference information does not include such data for flows of 800 m3/s, it is not possible to deduce the probability from the given chart or information. Therefore, the correct answer to the question is (c) Can't deduce from the information on the chart.