5 platters ,each platter has 2000 tracks each track 50 sectors with size 512 bytes
so T=50x512 /1024 =25 K
Hence option 3) is right ans
tried to add complete questions of UGC NTA NET..
But only admins can do that..!!!!
So finally, being big fan of Sanjay Sharma Sir, putting the link for complete question paper and official answer key here: https://ugcntanetcomputerscience2020paper.blogspot.com/