Auto Answer App.
Add your close contacts to the app's contact list. Enable the app. That's it. When you get calls from these contacts, app will answer it for you. App will wait for 5 sec before auto answering the call.
Just before driving your car, enable this app and enjoy your driving. If you get a call from your partner, app will automatically answer it for you.
*Disclaimer*: The call rejection feature is depends on the manufacturer and model of the device. So, App might not work properly in some models.
If you want to delete any contacts from the app's contact list, do a long press on the contact item.