Imagine that you are creating a web form where the overallRating element is a selection list displaying the options $$Excellent$,$Good$,$Okay$,$Poor$,$ and $$Terrible$.$ After assigning a couple of variables with the following JavaScript code, you can use the selectedIndex property to $\_\_\_\_\_.$

let custFeedback $=$ document.forms.custFeedback;

let overallRating $=$ orderForm.elements.overallRating;

a$.$

return the numeric value assigned to theoverallRatingoption selected by the user

b$.$

perform calculations using theoverallRatingoption selected by the user

c$.$

identify the string displayed to the user once they select anoverallRatingoption

d$.$

retrieve the index number for theoverallRatingoption selected by the user