Explanation:

- Trademark: These are recognizable signs, designs, or expressions identified with a product or service, which can indeed be sold under the Sale of Goods Act.

- Patent: A set of exclusive rights granted for an invention, allowing its owner to exclude others from making, using, or selling the invention, thus it can be sold too.

- Goodwill: Refers to the established reputation of a business and is often considered a valuable asset that can be sold or transferred as part of a business sale.

- All of the above: All these options can be considered as subject matter under the Sale of Goods Act.