• enable you to publish custom queries to your team’s AMC instance
• allow you to run a single query across multiple instances in parallel
• eliminate the need to hard-code values directly into your SQL code

The correct answer is: eliminate the need to hard-code values directly into your SQL code

Explanation: Check the official article: Custom parameters on the query editor

Custom parameters allow you to define placeholders in your SQL queries that are replaced by values at execution time. This means you do not need to hard-code values within the SQL code itself. Instead, you can specify and change parameter values before running the query, making your queries scalable and reusable. As a result, you can easily update your queries to run for different sets of values without needing to manually edit the SQL statement each time.​