Final answer:
When defining an icon set's conditional formatting in Excel, the Type should be changed first since it resets the comparison value to zero. This is important as it influences how data is evaluated and compared against your criteria, before customizing the icons and values.
Step-by-step explanation:
When defining an icon set's conditional format in Excel, the initial step is crucial as it can affect subsequent choices. The correct action to take first is:
Option c: When defining an icon set's conditional format, always change the Type first, because it changes the comparison value back to zero.
Setting the Type first is important because it defines how Excel will compare the data to certain criteria. Excel provides several preset Types in conditional formatting rules that dictate how icons are applied based on the values in your cells. After setting the Type, you can then go ahead and customize the icons and values according to the specific needs of your dataset. Remember, the sequence in which you set these parameters can affect the outcome and visual representation of your data.