What is the difference between "Variable" and "$"?

You are creating several new standard bead entries and want to use variables in your standard text.
What is the difference between “Variable” and “$”?

A.
Variable pulls in a dynamic value from the database and $ is a fixed variable.

B.
Variable pulls in a dynamic value from the database and $ allows the agent to enter a value.

C.
Variable is a fixed value and $ pulls in a dynamic value from the database.

D.
$ pulls in a dynamic value from the database and Variable allows the agent to enter a value.

E.
$ allows the agent to enter a value and Variable is a fixed value.