ANSWERS
A. 3.61 m/s²
B. 24.58 m/s²
C. 3.31 m/s²
Step-by-step explanation
The gravitational field constant of a planet is given by,

Where m is the mass of the planet, r is the radius of the planet and G is the gravitational constant, 6.67x10⁻¹¹ m³/kg*s².
For each of these planets, we have to replace m and r to find their gravitational field constants.
A. Mars,
![g_(Mars)=6.67*10^(-11)m^3/kg\cdot s^2\cdot\frac{6.37*10^(23)\operatorname{kg}}{(3.43*10^6m)^2}\approx3.61m/s^2]()
B. Jupiter,
![g_(Jupiter)=6.67*10^(-11)m^3/kg\cdot s^2\cdot\frac{1.90*10^(27)\operatorname{kg}}{(7.18*10^7m)^2}\approx24.58m/s^2]()
C. Mercury,
![g_(Mercury)=6.67*10^(-11)m^3/kg\cdot s^2\cdot\frac{3.28*10^(23)\operatorname{kg}}{(2.57*10^6m)^2}\approx3.31m/s^2]()