Please answer the following question: Read the article and select the best answer. Article: It took courage to stand up at work. Now more and more people like to have a change and stand up when they are on something important. Standing up is popular. Medical researchers have found that people who stand at work tend to be much healthier than those who sit. In the last few years, many office supply companies have begun to sell the adjustable- height desk. These so- called " sit/ stand" models are equipped with an electric motor that lets them shift from chair height to person height at the push of a button. Unfortunately, they're regarded as specially furniture. Sit/ stand desks tend to be expensive, hard to find and not easy to test it in person. When you worked standing up, your mind was more excited and new ideas kept coming out. This is because when you're standing, you feel a bit _ from your desk. If you got stuck on a word or sentence as you wrote, you found yourself shaking your arms, bouncing on your feet or stepping away from the desk for a bit------ things you couldn't do in a chair. Often, standing up seemed to relax your mind enough for you to get over creative barriers. There's one other thing about standing for a long time; you tended to get hungrier than you do when you sit on a chair. That felt like confirmation of the stand-up advocates' belief that you burn more calories when you stand than when you sit. For this reason alone, I'm hoping that sit/ stand desks one day hit the mainstream, with mass- market furniture companies making many low- priced versions. We could all do with a bit more standing up. Question: We can learn that the adjustable- height desk is _ . Options: A: easy to find B: easy to test C: relatively cheap D: smart in operation
Answer:
D