For a moon orbiting its planet, r p is the shortest distance between the moon and its planet and r a is the longest distance between the moon and its planet. What is a moon's orbital eccentricity if r p is equal to 0.27r a?

A. 0.57

B. 0.27

C. 0.48

D. 0.65

The eccentric formula for ellipse can be calculated using

e = (r_a - r_p) / (r_a + r_p)

r_a is the longest distance between the moon and its planet

r_p=0.27 r_a is the shortest distance between the moon and its planet

Then,

e = (r_a - r_p) / (r_a + r_p)

e = (r_a - 0.27 r_a) / (r_a + 0.27 r_a)

e = 0.73r_a / 1.27 r_a

e = 0.57

This is the moon orbital eccentric