Here's why:
* "Set" is singular: The word "set" itself is singular, meaning it refers to one group or collection.
* Focus on the group: When you say "a set of," you're focusing on the group as a whole, not the individual items within it.
Examples:
* Correct: "A set of keys was on the table."
* Incorrect: "A set of keys were on the table."
Important Note:
Even though the items within the set might be plural, the verb agrees with the singular "set."