Answer:
B.The value k is constant for each of the eight planets in our solar system.
Step-by-step explanation:
Kepler's third law states that the square of orbital period of the planet is proportional to the cube of semi-major axis.
P² = k A³
k is constant for all the planets in the solar system.

Where, G is the gravitational constant and M is the mass of the Sun.
The orbital period is measured in units of time, and the semi-major axis is measured in units of distance.
With increase in length of the semi-major axis, the orbital period increases.
The value of k can be found by: P²÷A³.