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 and4th XXOXOXX ⇒ O’s place 3rd and5th XXXOXOX ⇒ O’s place 4th and6th XXXXOXO ⇒ O’s place 5th and7th..