Let’s examine each asset:

1. Brand recognition: This is considered an intangible asset. It represents the value associated with a brand’s reputation and customer awareness, but it has no physical presence.
2. Inventory: This is not considered an intangible asset. Inventory refers to the goods a company holds for sale and is a physical, tangible asset.
3. Intellectual property: This is an intangible asset. Intellectual property includes patents, copyrights, trademarks, etc., which are valuable but non-physical in nature.
4. Mailing list of clients: This is also considered an intangible asset. While it may exist in a physical form (as a database), the value lies in the relationships and potential business it can generate, making it intangible.

Thus, three of the four are intangible investments. The correct answer is Only three.