Read the passage below carefully, and then choose the best answer:
Getting Focused and Flexible with Yoga
In a small room, men and women are getting a great workout. However, there are no weights in this gym. The only piece of equipment is a small rubber mat. On it, they strike unusual poses which are held for minutes at a time. An instructor goes from student to student urging them to relax and breathe deeply, while inspecting their posture. In the end, through the art of yoga they hope to balance their body, mind, and spirit. Yoga originated in India over 2,000 over years ago. The first yogis weren’t looking to lose weight or get themselves in great shape. Instead, they practise yoga to help them achieve liberation. Yoga became an important part of Hindu culture, and it is mentioned in nearly all of the religion’s ancient scriptures. It wasn’t until the 19th century, however, that Westerners took notice of yoga. In the 1890s, Swami Vievekananda became the first yoga teacher to take on Western students when he toured the US and Europe. His lessons focused primarily on the spiritual aspects, and his speeches intrigued many intellectuals, but it would take some time before yoga would catch on with the masses. That didn’t happen until the 1980s when many Americans and Europeans embraced yoga during a worldwide exercise boom. Yet once it took hold, yoga has increased popularity year by year. It is estimated that over 20 million Americans now practice yoga regularly. A main reason why contemporary people are hooked on yoga is that it helps to relieve work-related stress. Students are taught to breathe slowly and deeply while concentrating on the present moment and letting go of the past. The challenging postures help to balance the negative effects people experience from sitting in chairs all day. The poses also help people to regain flexibility and improve circulation, which is particularly useful to the elderly. As yoga became commercialized in the West, many new branches were formed. Ashtanga yoga moves at a fairly quick pace, flowing from pose to pose, power yoga, on the other hand, offers workouts that are designed to increase strength. Another popular style, hot yoga, has students practise in hot environments to help them burn more calories. If you are thinking of studying yoga, try them all and let your heart decide which one is best for you.
3. The word “that” in paragraph 2 refers to __________