The correct answer is D. Only A and B.
The active cell is the cell that is currently selected. It is defined by a bold border around the cell. The user enters data into the active cell. The formula bar is located above the active cell and is used to enter formulas.
Option A is correct because the active cell is defined by a bold border around the cell.
Option B is correct because the user enters data into the active cell.
Option C is incorrect because the formula bar is located above the active cell, not the active cell itself.