Detailed Instructions: In this task, you are given a context and four options. Each option is a suggested ending for the context. You should read the context and pick the best ending for the context. Please answer with "A", "B", "C", and "D".
Q: [header] How to use a treadmill [title] Warm up your joints and muscles by walking before running. [step] Your joints and muscles work best when they're warmed up for about 5 minutes. Get your blood flowing by walking at a slow pace on a slight incline, such as at a 2% incline. <sep> (A) This will help you avoid injuries such as muscle strains or tears. [substeps] Follow your run with a few minutes of walking to cool down. (B) [substeps] Do some jogging laps on your treadmill over the span of two to three hours before you start running. Turn on some upbeat music in the background before you begin your run. (C) You can also walk for an additional 5 to 10 minutes. [substeps] For example, you might be able to do a 3 km (4 mi) walk during 15 minutes. (D) You can also use a treadmill for other purposes such as swimming. [substeps] If you're warm-up, break it up into two forms: walking, running, and biking.
A:
A