Explanation:

- The word "equivocal" is often used to describe language or statements that are open to more than one interpretation, making them unclear or ambiguous.

- Option 1: Certain – This means clear, definite, or having no doubt, which is the opposite of equivocal.

- Option 2: Ambiguous – This means open to more than one interpretation or not clear-cut. It aligns perfectly with "equivocal."

- Option 3: Manageable – This refers to something that can be controlled or dealt with easily, not related to the concept of being unclear or open to interpretation.

- Option 4: Vicious – This describes something intentionally harmful or spiteful, not related to unclear communication.

Your understanding of the highlighted word is spot-on.