Explanation:

- Option 1: Words

- Offers can be expressed verbally or in writing, but implied offers go beyond just spoken or written words.

- Option 2: Conduct

- Implied offers can indeed be proven through actions or behavior. Conduct might demonstrate an intention to offer without explicitly stating it.

- Option 3: Circumstantial Evidence

- Circumstantial evidence can support the existence of an implied offer but doesn’t directly prove it; it's more of an inference.

- Option 4: Prima Facie Evidence

- This refers to evidence sufficient to establish a fact unless rebutted. It relates more to the evidence's weight than proving an implied offer.