When you catch the ball you act surprised, action- reaction
It would be A. Because think of the explanations Jasons friend could say to them that would be a negative 'statement'.
"Frequency" just means "often-ness" ... how often something happens.
It's always expressed as
<em>(number of happenings) / (some period of time) .</em>
It is an example of liquid. if thats what you are asking for...