Input Fields Options – default option for drop-down list

Hey I need some help with the default selection on the drop down list. On the input field some customers don’t select the option even though it is set to a required field, there is already a option selected by default. which means it does not trigger an error on for required and just goes with the default option.

How do I change this to say something like -select option- and it triggers an error on form when the customer does not select an option.