Volume of a sphere = 4/3 × πr³. Substitute r=7: volume = 4/3 × 22/7 × 7³ = 1437.33 cubic mm. A sphere is a fully round solid, so its volume depends on the cube of the radius, r³. Cubing the radius means multiplying the radius by itself three times before applying 4/3π. The answer is in cubic units, so the correct choice is 1437.33 mm³.