Yes, you can apply RTI to obtain Copies of your Answer Sheets from Andhra Pradesh Public Service Commission (APPSC).
APPSC was established under Article 315 of the Constitution of India and its functions are enumerated in the Article 320 of the Constitution of India. The Commission came in to existence on 1st November, 1956 with the formation of the State of Andhra Pradesh. APPSC is a "Public Authority" as per Section 2 (h) of the RTI Act of 2005 and comes under its ambit.
You can file RTI to obtain Certified Copies of your Answer / OMR Sheets under Section 2 (j) of the RTI Act from APPSC by addressing the same to the designated "Public Information Officer (PIO)" through Registered Post and by paying the prescribed fee. You should attach a Copy of your Admit Card and mention your Roll No., Registration No., Name of the Exam clearly in the Application.
To know more about the procedure to file RTI Applications for Answer / OMR Sheet, please refer https://onlinerti.com/how-to-file-rti-online-for-exam
To know more about the procedure to file RTI in Departments of Andhra Pradesh, please refer https://onlinerti.com/how-to-file-rti-online-for-andhrapradesh