A Pair of Stars Orbit Around One Another in an Elliptical

Multiple Choice

A pair of stars orbit around one another in an elliptical orbit with a semimajor axis,"a",of 1 AU with an orbital period,"P",of 1 year.What is the mass of the pair of stars?

A) m₁ + m₂ = a³ / P² = 1 solar masses
B) m₁ + m₂ = a³ / P² = 2 solar masses
C) m₁ + m₂ = a³ / P² = 4 solar masses
D) m₁ + m₂ = a³ / P² = 8 solar masses
E) m₁ + m₂ = a³ / P² = 16 solar masses