which-of-the-following-statement-is-correct-5e8ac85c0044163febd17547

Which of the following statement is correct?

Once a reference variable has been defined to refer to a particular variable it can refer to any other variable.
A reference is indicated by using && operator.
Once a reference variable has been defined to refer to a particular variable it cannot refer to any other variable.
A reference can be declared beforehand and initialized later.