#### Answer

The correct answer is c. 11.9 years

#### Work Step by Step

Let $M_s$ be the mass of the sun.
Let $R$ be Jupiter's orbital radius.
We can write an expression for the period $T$ of Jupiter's orbit.
$T^2 = \frac{4\pi^2~R^3}{G~M_s}$
$T = \sqrt{\frac{4\pi^2~R^3}{G~M_s}}$
Since the period does not depend on the mass of the object in orbit, any object with the orbital radius of $R$ around the sun would have the same period. Therefore, the earth would also have a period of 11.9 years.
The correct answer is c. 11.9 years.