The functions in Microsoft Excel must always begin with the equal sign (=).
The answer is C) =.
This is because the equal sign tells Excel that the sequence of characters that follows constitutes a formula. For instance, in Excel, if you want to add 2 and 3, you would type =2+3 into one of the cells. In this case, the equal sign indicates that Excel should treat the part that comes after as a function or formula to evaluate.