What term describes a process or action that requires considerable effort or energy?

The term that describes a process or action that requires considerable effort or energy is "strenuous." This word is often used to characterize activities that demand a high level of physical exertion, such as intense exercise or challenging tasks that can lead to fatigue. The connection to physicality is paramount; for example, a strenuous workout would push the body to its limits, necessitating endurance and vigor.

In contrast, the other choices focus on different themes. "Just what the doctor ordered" refers to something that is beneficial or desirable, especially in a health context, but does not imply the effort required. An "offering of fake cure" pertains to fraudulent health remedies and has no connection to the level of energy involved in activities. Lastly, "green around the gills" is an idiomatic expression used to describe someone who looks ill or nauseous, again irrelevant to the concept of effort or energy expenditure. Thus, the use of "strenuous" accurately conveys the intent of the question regarding demanding activities.