Multi-choice problem: Continue writing the next sentence in this paragraph:

How to make rocky road brownies
Preheat the oven.
To ensure that the oven is hot enough for the brownies when you're ready to bake them, it's important to preheat it. Set the oven temperature to 350 degrees fahrenheit (177 degrees celsius), and allow it to fully heat.

Options are: a. Keep an eye on your oven so you know when it's preheated. Most models flash an indicator light or beep to alert you.. b. Once it's heated, you can prepare the brownies. If you don't have access to a preheated oven, you can skip this portion of the process by pressing the stop button on the bottom of your oven.. c. Cream the butter and sugar in a medium mixing bowl. Once the butter and sugar are fully melted, put the two large eggs and butter into a separate medium mixing bowl.. d. Most ovens require specific methods when preheating the oven. Check on the oven's preheating instructions or ask a store employee in the baking section for ideas..
a.