Answer:
There are 2 Valve Systems
Explanation:
The mitral valve and tricuspid valve are located between the atria (upper heart chambers) and the ventricles (lower heart chambers).
I'm not entirerly sure whether ANY of these statements could be considered untrue.
Socializing up to a certain extent could increase productivity, granted it would be done with work in mind.
B, C, D all are true as these are very commonplace things that can happen at the workplace, while not all are equally probable all of them could happen.
If one really is considered untrue, it most likely would be A.
