Read the following passage and mark the letter A, B, C, D on your answer sheet to indicate the best answer to each of the following questions from 23 to 30.

If you’re new to running, or new to marathons, you might be worried about or even fearful of the distance. And these feelings are completely understandable, given the fact that more than 42 kilometres is a very long way. However, more and more people are taking on this challenge every year, and for very good reasons.

Obviously, running such a long distance requires a lot of training, and the more you train, the more your endurance will be enhanced. And of course, as you become more physically active, your heart and muscles will be stronger, your blood circulation will improve, and you will most likely get in shape in no time. Additionally, there are also mental and social benefits such as feeling less stressed and more energized as well as having the chance to meet and establish meaningful relationships with other people.

If you think about it, running a marathon is also a chance for personal development. Everyone has at least one fear or insecurity, and for many people, completing a marathon race can seem like an extremely daunting or even impossible task. Of course, it’s true that this is a big challenge that requires commitment and perseverance. That being said, every time you step outside out of your comfort zone and accomplish something new, you will grow stronger and become more confident.

Sometimes, you can actually help many others when you run a marathon. Many runners now combine their marathon goal with the goal of helping others by participating in races that raise money for charity. Besides, running in such marathon races will most likely give you all the motivation you need to get through the exhausting 42-kilometer run. After all, it’s quite difficult to quit when you know that you are giving help to people in need.

(Adapted from active.com)

The word ,“this” in paragraph 3 refers to _________.