Why is the definition for second based on the Cesium 133 atom?

1.The rate of vibrations of the atoms is fixed.

2,The rate of vibrations of the atoms is precise.

3.The rate of vibrations of the atoms is consistent.

4.The rate of vibrations of the atoms is easily observed.

I've boiled it down to either 2 or 3, was leaning more towards 2, anybody help meh?

Question

Why is the definition for second based on the Cesium 133 atom?

1.The rate of vibrations of the atoms is fixed. 

2,The rate of vibrations of the atoms is precise. 

3.The rate of vibrations of the atoms is consistent. 

4.The rate of vibrations of the atoms is easily observed.

I've boiled it down to either 2 or 3, was leaning more towards 2, anybody help meh?

anonymous · Answer

You're probably right, precise as in as close to correct as possible. While consistency could be consistantly incorrect.