The correct answer is C. Pressing the Esc key.
Option A, pressing an arrow key, can be used to enter data in a cell by moving the cursor to the desired cell and then typing the data. Option B, pressing the Tab key, can be used to enter data in a cell by moving the cursor to the next cell in the row. Option D, clicking on the formula bar, can be used to enter data in a cell by clicking in the formula bar and then typing the data.
Option C, pressing the Esc key, cannot be used to enter data in a cell. The Esc key is used to cancel an action or to exit a menu.