Step-by-step Solution:

Let the total number of trees in the row be ( n ). The problem states that one tree is the 'fifth from either end' of the row. This means that the position of the tree is counted as the 5th tree from both the left end and the right end. \[\] When a tree is the fifth from either end, the positions from both ends must satisfy the equation:\[\] n - 4 = 5 \[\] Step 1: Set up the equation The logic here comes from the symmetric positions in the row. The distance from the fifth position from one end to the other end would leave the same number of trees on either side:\[\] n - 4 = 5 \[\] Step 2: Solve for ( n )\[\] n = 5 + 4 = 9 \[\] Final Answer:\[\] The total number of trees in the row is 9. \[\] \[\] Correct Answer: (b)