Option D - an equal sign.
An equal sign is the first thing that you have to enter when typing an equation into a cell. All formulas in Microsoft Excel start with an equal sign (=). For example, if you need to sum up two cell (cell A and cell B), you will write your formular this way: = A + B
You always begin by placing the equals sign into a cell. This is because the cell has to equal the value, and the formula.
For instance, if your spreadsheet needed to add the values of (say) different months' income, then the equals sign refers to the total of the different cells. i.e. you are finding what value that total equals.
The first thing that you have to enter when you want to write a formula through excel is the equal sign. If you would start the formula with something else, expect that you are going to get the error message. A red triangle may appear on the side of the cell. Excel is a very useful platform that people use not only for computations but for creating tables, charts, and graphs easily.
People use this in order to enter various information that will be computed or displayed. There are some companies that do not accept potential employees who do not know how to use this program. It is vital that you learn more about how to use this. It will help you at work a lot.