What defines a field's description dynamically in different queries?

The correct answer is a liquid variable because it allows users to define the field's description dynamically based on certain conditions or parameters at runtime. Liquid is a templating language that enables you to insert dynamic content into Looker fields. By using liquid variables in the description of a field, you can customize the information based on user input, environment settings, or other contextual data. This capability is especially useful if you want to provide specific context or changes in the descriptions depending on how a query is executed or the data being viewed.

In contrast, while field filters, attribute variables, and dimension groups are important concepts in Looker, they do not provide the same dynamic customization for field descriptions. Field filters are used to limit the data returned based on certain criteria, attribute variables help in creating derived fields based on existing ones, and dimension groups are meant for grouping dimensions, particularly in time series analysis. None of these features interact with the field description in a dynamic manner like liquid variables do.