Explanation:

- Wad typically refers to a bundle or a thick mass of something.

- Option 1: Gesture

- Gesture is a movement of part of the body, especially a hand or the head, to express an idea or meaning. It doesn't match the meaning of wad.

- Option 2: Quantity of documents or banknotes

- A wad can refer to a bundle or a roll, especially of paper items like documents or banknotes.

- Correct Answer

- Option 3: Surface

- Surface refers to the outside part or uppermost layer of something. It’s not similar to the concept of a wad.

- Option 4: Miracle

- A miracle is an extraordinary event that is not explicable by natural or scientific laws. It doesn't relate to the meaning of wad.