(a) The requirement is to identify how each specific cell
within a spreadsheet is identified. Answer (a) is correct because
each cell has an address, composed of a combination of its column
and row in the spreadsheet. Answer (b) is incorrect because
the column portion of the address is not specific to the cell. Answer
(c) is incorrect because the row portion of the address is not
specific to the cell. Answer (d) is incorrect because no diagonal
is ordinarily used to identify a particular cell.