Answer: Option 'B' is correct.
Explanation:
Since we have given that
A weather forecasting website indicated that there was a 90% chance of rain in a certain region.
Based on above report, we can conclude that there is 0.90 chances of rainfall in a particular region.
So, there is a 0.90 probability that it will rain somewhere in the region at some point during the day.
Hence, option 'B' is correct.