In the given sequence, the position of O is increasing in every position from the front to the back. OXOXXXX ⇒ O’s place 1st and 3rd XOXOXXX ⇒ O’s place 2nd and 4th XXOXOXX ⇒ O’s place 3rd and 5th XXXOXOX ⇒ O’s place 4th and 6th XXXXOXO ⇒ O’s place 5th and 7th.