Not to sound like a snob, but isn't the program suppose to teach us and not us correcting it?
What if we are extremely new and have no idea at all about which is the correct one? Then we will be learning the wrong thing.
to expand on what I said previously, said alone "¿estás?" would be understood as "are you there?"
This was originally correct and a new entry should have been created for ¿estás...? which would be "are you...?"