How should a function's vector parameter ages be defined for the following situations?

ages will always be small $($fewer than $10$ elements$)$ and the function will not modify the vector.

Constant and pass by reference.

Constant but not pass by reference.

Pass by reference but not constant.

Neither constant nor pass by reference.

ages will always be small, and the function will modify the vector.

Constant and pass by reference.

Constant but not pass by reference.

Pass by reference but not constant.

Neither constant nor pass by reference.

ages may be very large, and the function will modify the vector.

Constant and pass by reference.

Constant but not pass by reference.

Pass by reference but not constant.

Neither constant nor pass by reference.

ages may be very large, and the function will not modify the vector.

Constant and pass by reference.