Answer: Option (C) is the correct answer.
Step-by-step explanation:
The relation between mass and weight is as follows.
Weight = mass × g
where, g= gravitational force =

For mass = 2m, calculate the weight as follows.
Weight = mass × g
= 2m × g
= 2mg
This means that when mass of object becomes 2m then its weight will also become 2mg.
Therefore, we can conclude that if the weight of an object of mass "m" is "mg," then the weight of an object of mass "2m" is 2mg.