Sign 15 if the person you want to talk about is not in the room where should you index him or her? a: on the dominant side b: on the non dominant side c: toward his or her actual location d: nowhere in particular

Indexing is when you point your index finger at a person who is or isn't in the signing area. Sometimes we call that "present referent" and/or absent referent.

If the person is there, (present) you can just point at him to mean "HE" or "SHE."  You can point at an object to mean "IT." 
 

If the person is not there, you can identify him by spelling his name (or some other method of identification--like a "name sign," or maybe someone else has spelled his name, or he was sitting in a chair and then got up and left), then you can "index" him to a point in space. Now you have a referent for that person.  Once you have set up a referent, you can refer back to that same point each time you want to talk about that person. 
 

In American Sign Language, the index or forefinger handshape is used to indicate the pronouns "me," "you," "he-she-it," "we," "you-all," and "they."  (Some people just fingerspell words like "SHE, HE, THEY..."

To sign "me" you just point at yourself or touch your index finger to your chest.

I got it off of Google hope I helped you!
I'm a beginner at asl too