Weight of the object is given as

so weight of the object will be maximum where gravity(g) will be maximum
so here out of all given four the gravity "g" will be maximum at the surface of SUN as we know that sun will be of maximum mass out of all four planets
as we know that

so correct answer will be
3. SUN
Zeroth Law of Thermodynamics, which in turn will mean the heat will transfer between both of them up to the point where they are in thermodynamic equilibrium. So the answer is C.
D = v^2 / 2ug
d= 3.5^2 / 0,15 x 9.8 m/s^2
the answer should be around 4.2m
hope this helps