Two of the following statements are true, and one is false. Identify the false statement:

a$.$ An optional parameter to a method is one for which an argument can be a value parameter, a ref parameter, or an out parameter.

b$.$ You make a parameter optional by providing a value for it in the method declaration.

c$.$ If you assign a default value to any variable in a method's parameter list, then all parameters to the right of that parameter must also have default values.