**QUESTION:**

The set of fourth roots of unity are closed with respect to?

**OPTIONS:**

- Addition
- Division
- Subtraction
- None of the above

**CORRECT OPTION:**

Division

**EXPLANATION:**

Set = {1,-1,i,-i}

Addition: 1 + i is not part of the set;

Subtraction: 1 – i is not part of the set;

Any division operation in the set results in an element which is part of the set. E.g. 1/i = i/i^{2} = -i. Hence it is closed w.r.t division;

Remember that set of fourth roots of unit are closed w.r.t multiplication and division.

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