Which of the following sets are closed? Choose ALL that apply. Show the steps. I. The set of negative integers under addition II. The set of negative integers under multiplication III. The set of...

Which of the following sets are closed? Choose ALL that apply. Show the steps.

I.

The set of negative integers under addition
II.

The set of negative integers under multiplication
III.

The set of positive integers under addition
IV.

The set of integers under division