Final answer:
The modal verb 'should' in the provided sentence expresses probability that the sun will come out by noon, aligning with Choice B; it is not used to give advice.
Step-by-step explanation:
In the sentence 'I checked the forecast, and the sun should come out by noon,' the bold modal verb should is being used to express probability. This means that according to the speaker, based on the information available (like a weather forecast), there is a likelihood or expectation that the sun will appear by noon. This usage corresponds with Choice B: This sentence uses should to express that the sun will probably come out. The modal verb should here does not indicate giving advice, which eliminates the option that it is used to give advice (Choice A).