To ascertain the total number of individuals in the sequence, we analyze the locations of A and B, along with the count of individuals situated between them. A occupies the 7th position from the left, and B is the 9th individual from the right. Fifteen people are positioned between A and B. The total count of individuals is determined by the formula: \[ \text{Total} = (\text{A's position from left}) + (\text{People between A and B}) + (\text{B's position from right}) \] \[ \text{Total} = 7 + 15 + 9 = 31 \] An alternative perspective, considering inclusive positions for A and B, requires adjustment to prevent double enumeration. Nevertheless, the direct summation accurately represents all positions: 7 (extending to A) + 15 (between A and B) + 9 (from B to the conclusion) = 31. Consequently, option (2) is validated. Options (1), (3), and (4) do not align with the computed total.