On a grid coordinate of 2.5/E.4, the 2 represents the

• A. Horizontal grid line
• B. Vertical grid line
• C. Grid line number
• D. Grid square

Answer: (B)

In this grid system, the left-hand portion identifies which vertical grid line you’re aligned with. The number 2 points to the vertical line labeled 2, which sets your position along the horizontal direction. Vertical grid lines run top to bottom, so picking the line numbered 2 tells you you’re in that column. The horizontal placement is determined by the part to the right of the slash, which uses a horizontal line (often a letter) and possibly a square, not the number itself. So the 2 represents the vertical grid line.