24. A hypothetical planet orbits a star with mass one-half the mass of our sun. The planet's orbital radius is the same as the Earth's. Approximately how many Earth years does it take for the planet to complete one orbit?
(A) 1/2
(B) 21
(C) 2
(D) 2
(A) 1/2
(B) 21
(C) 2
(D) 2