The question asks for the number of cells that contain data in row 1 of the given table. In spreadsheet terminology, a row is a horizontal line, and a cell is a box where a row and column intersect. Looking at the table, row 1 contains the following data: 'BOOKS', 'SUPPLIED', 'TO SENIOR', 'HIGH', and 'SCHOOLS'. Therefore, 5 cells in row 1 contain data.