Here we have odd parity at row r1 and columns d5,d2 and d0.
Now since only 1 row shows error it can be (r1,d0) or (r1,d2) or (r1,d5)-----> any one of the three possible choices.
suppose it is (r1,d2).
Now still we are left with two errors at d0 and d5 but there is no error in any other row. It means error is at same row but two columns d0 and d5 and hence row parity could not detect it.
example- it could be r2,d0 and r2,d5 or r3,d0 and r3,d5 or any such choice.
so we can have minimum three bit error here.