1. Sentences that state a fact or an opinion are written in the indicative (A).
The indicative mood expresses facts, opinions, assertions, and questions. It is the most common verb mood.
2. Which verb mood would work the best for stating your opinon about a topic would be the indicative (A).
As stated in question 1, the indicative mood can express opinons.
The imperative mood expresses commands. The subjective expresses a wish or expresses something that is opposite of what is really true. The conditional is based on a condition.