Answer: The correct answer is option a.
Explanation:
Basic unit to measure mass is defined as the unit which is commonly used to measure the mass of an object.
From the given options,
Option a: Grams is a unit which is used to measure mass and it is the commonly used unit.
Option b: Cubic meter is the unit which is used to measure the volume of an object.
Option c: Metric ton is a unit which is used to measure the mass of an object but this unit is not commonly used. hence, this is not basic unit to measure mass.
Option d: Meter is the unit which is used to measure length.
From the above information, the correct answer is option a.
