Which of the following is true regarding defense to trademark infringement?

Multiple Choice

• One defense to trademark infringement is that the mark is not descriptive or generic.
• One defense to trademark infringement is that the mark is not distinctive.
• The defendant argues that the mark has become invalid since its trademarking.
• One defense to trademark infringement is that the use is an "unfair use."
• The defendant argues that using a rival's trademark in comparative advertising is illegal.