Hii

If you are asked to choose 3 preferences for exam center, you are suggested to choose the most nearest city ( if your own city is not listed ) so that you dont have to face any problem on the exam day to reach the center.
Since the official prospectus is yet to be released, so there is no confimation about the exam cities, but as per last year data it was seen that in the state of telangana, there were 3 cities which had exam centers for the entrance namely-

• Hyderabad
• Warangal
• Karimnagar
  

And from Andhra Pradesh, the cities were as follows-

• Chirala
• Guntur
• Kurnool
• Kakinada
• Nellore
• Rajamundry
• Tirupati
• vijayawada
• Visakhapatnam
• Vizianagaram

It is likely that the number of centers remain same and cities also be same and so i would suggest you to choose wisely the best option which would be easy for you to reach. There is no issue if you choose a city from Andhra Pradesh also if it is easy for you to reach there.
As far as i know, you are supposed to choose only 1 option and then the center is alloted as per the availability of seats on a first cum first basis. 
So choose very wisely as you will not be allowed to make any changes after submitting the application.
Feel free to revert back incase of any doubt.

Hope this helps
Thanks!!