Which of the following describes a process explanation?

a step-by-step process, such as a math formula or a scientific technique

an explanation of how events in history contributed to or resulted in other events

educated guesses about future events based on knowledge of cause-and-effect relationships

a method of organization

Given that a process explanation refers to a detailed explanation of how something is done by presenting every single step of the process, I'd say the correct answer is the first option - a step-by-step process, such as a math formula or a scientific technique. The other options do not really have anything to do with steps within a process or how to complete it, which is why they are not correct.