Whats the question exactly?
Time period of any moon of Jupiter is given by

from above formula we can say that mass of Jupiter is given by

now for part a)

T = 1.77 day = 152928 seconds
now by above formula



Part B)

T = 3.55 day = 306720 seconds
now by above formula



Part c)

T = 7.16 day = 618624 seconds
now by above formula



PART D)

T = 16.7 day = 1442880 seconds
now by above formula



Answer:
a = 2 m/s^2
which agrees with the third answer option provided.
Explanation:
Recall the kinematic formula for displacement under the action of a constant acceleration "a":
yf - yi = 1/2 a t^2
using the information provided this equation becomes:
9 = 1/2 a (3)^2
solve for a:
9 * 2 / 9 = a
then a = 2 m/s^2
which agrees with the third answer option provided.