Final answer:
A trademark must be registered to support a trademark infringement action. Registration provides legal protections and rights to the owner, enabling them to enforce their rights and seek remedies for infringement.
Step-by-step explanation:
A trademark must be registered in order to support a trademark infringement action. When a trademark is registered, it provides the owner with certain legal protections and rights. If someone infringes on a registered trademark, the owner can take legal action to enforce their rights and seek remedies such as damages or injunctive relief. Without registration, it may be more difficult to establish and enforce trademark rights.