Question

A set is _________ under an operation (such as addition, etc) if any two elements of that set always generate another element IN the set, when the operation is performed on them.

Answer 1

If any two elements of the set always generate another element in the set itself, when an operation is performed on them, then that property is called CLOSURE.

Also, that set is said to be CLOSED under that operation.

Hence, the correct answer to fill the blank is CLOSED.