Respuesta :
Answer:
it's (4)
The set of integers is closed under the operation of addition because the sum of any two integers is always another integer and is therefore in the set of integers.
in (4) set of all even numbers {2, 4, 6, 8, 10,......, inf.}
2+4=6 (element of the set)
4+6=10 (element of the set)
so the answer is (4) {x|x is an even integer}
Step-by-step explanation:
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