Concept:For any regular polygon, the sum of all exterior angles is 360∘. Since all exterior angles are equal, each exterior angle is n360∘.Explanation:Each exterior angle of a regular polygon with n sides is given by:Exterior angle=n360∘Given that each exterior angle is 45∘, we set up the equation:45∘=n360∘Multiply both sides by n:45∘n=360∘Divide both sides by 45∘:n=45∘360∘=8Answer:n=8 Correct option: B. 8