Explanation:

- Option 1: A probability.

- Generally refers to an idea or expectation of something happening.

- Does not imply surety.

- Option 2: A certainty.

- Implies sure and definite knowledge.

- Often considered a strong word indicating full awareness or assurance.

- Correct Answer

- Option 3: Both certainty and probability.

- Combines both ideas but does not fully express the definitive assurance of "knowledge."

- Creates ambiguity unlike knowledge under legal considerations.

- Option 4: None of the above.

- Suggests other options might be more accurate, which isn't the case here.