The correct way to describe how a verb in the conditional mood is formed is:
4. Using an auxiliary verb paired with a main verb to describe what will happen as a result of a solution.
In English, the conditional mood is typically formed using the auxiliary verbs "would," "could," or "might" paired with the base form of the main verb. For example, "I would go" or "If it rained, we might stay inside." This structure expresses hypothetical situations or outcomes based on certain conditions.