Putti,
ICAI, themselves, give information under Section 4,1, b, of the
RTI Act on the ICAI website:
ICAI-Announcement
Therefore, they are a Public Authority, as defined under the
RTI Act.
Please go through various threads in this forum (by using the search function) on the subject of "answer sheets".
You can then decide and use the
RTI Act to get information from ICAI.