A centimeter cannot measure mass because mass is measured by grams. 
Answer: Centimeter 
        
                    
             
        
        
        
Answer: acceleration due to gravity of planet a would be twice that of planet b. Given that the radius are thesame.
Explanation:
Acceleration due to gravity is as a result of the gravitational force of attraction of a planet to its centre.
g = GM/r^2
Where;
g = acceleration due to gravity
G = gravitational constant
M = mass of planet 
r = radius of planet
Given that the two planet have the same radius, if the mass of planet a is twice the mass of planet b the the acceleration due to gravity of planet a would be twice that of planet b, because acceleration due to gravity is directly proportional to the mass of the planet.
 
        
             
        
        
        
its the the first one u said
 
        
             
        
        
        
Answer:
The answer to your question is C
Explanation:
acceleration is a vector quantity because it has both magnitude and direction