Final answer:
A Snippet is an object in a system that contains content rules for use in landing pages or emails, facilitating dynamic and personalized content in marketing automation.
Step-by-step explanation:
The term Snippet best describes C. An object in the system where rules can be set to change content for use in a landing page or email. A snippet is often a dynamic piece of content that can be used across multiple emails or landing pages. For instance, a marketing team could create a snippet for a promotional message that is included in various email campaigns, and the content of the snippet can be automatically tailored to different segments of their audience based on pre-defined rules. Snippets are essential tools in marketing automation platforms for creating personalized and scalable communication strategies.