Concept:The sum of the interior angles of an n-sided polygon is (n−2)×180∘.This formula is derived by dividing the polygon into (n−2) triangles.Explanation:Let the polygon have n sides.Given sum of interior angles =1800∘.Using the formula: (n−2)×180∘=1800∘.Divide both sides by 180∘ to isolate (n−2).n−2=1801800n−2=10Add 2 to both sides:n=10+2=12Answer:The polygon has 12 sides.Correct option: B. 12.