Answer:
D.)=($A$1-$B$1)
Explanation:
The $ sign placed in between the characters of a cell makes the cell an absolute reference in any formula that involves the cell.
For example, the function "=A1 - $B$2" would give a result equivalent to "=A1 - B2" however, a drag down of the formula would result in a change of the function A1 to A2, A3, A4, A5...
Hence from the options, =($A$1-$B$1) is the only formula with absolute references.
