The horizontal and vertical lines on a spreadsheet are called:

The correct answer is: D. Grid-lines.

Grid-lines are the horizontal and vertical lines that divide a spreadsheet into cells. They help to organize data and make it easier to read.

Cells are the individual boxes that make up a spreadsheet. They are where data is entered and stored.

Sheets are the individual pages that make up a spreadsheet. Each sheet can contain different data or calculations.

Block lines are the lines that separate cells into groups. They are used to create tables and other structures.