The correct answer is option 2: ms-2, which stands for meters per second squared. Acceleration is the rate at which the velocity of an object changes, and it is measured in meters per second squared.

Let`s dissect each option to better understand why the correct answer is option 2:

Option 1: ms-1. This unit represents meters per second and is the unit of velocity, not acceleration. Velocity measures the rate of change of displacement, whereas acceleration measures the rate of change of velocity.

Option 2: ms-2. This is the correct unit for acceleration. It indicates that the velocity of an object is changing by 1 meter per second every second (or 1 meter per second squared).

Option 3: cms-2. This unit represents centimeters per second squared. While it is a unit of acceleration, the SI unit for acceleration is meters per second squared (option 2). It is important to use the SI unit for consistency and ease of calculations.

Option 4: kms-2. This unit represents kilometers per second squared. Again, while it is a unit of acceleration, the SI unit for acceleration is meters per second squared (option 2).

Therefore, the correct answer is option 2: ms-