Explanation:

- Option 1: The maxim "allegans contraria non est audiendus" translates to "he who alleges contradictory statements is not to be heard." This principle underlies estoppel, as it prevents a party from taking conflicting positions to the detriment of another who relied on the initial position.

- Option 2: Estoppel is also considered a rule of evidence. It prevents a party from presenting evidence that contradicts what has already been established.

- Option 3: Both (A) & (B) are valid, as estoppel involves principles of fairness and evidence in legal contexts.

- Option 4: None of the above is incorrect, as options 1 and 2 both apply.

Your Answer: Option 3 (Both A & B)

The Principle of Estoppel is indeed based on both the maxim and the rule of evidence.