阅读下面短文，从每小题所给的A、B、C、D选项中选出最佳选项。

    If you are really interested in music festivals, then you have probably heard of the Bestival Music Festival. It takes place every September on the Island of Wight, the UK. As it is at the end of summer, people think it's their last chance to go to a festival and have fun before going back to boring work.

    The dream begins as soon as you start traveling to the island. In order to get to the campsite (营地) of the Bestival, you have to take the ferry (渡轮). The ferry is full of happy festival lovers who are ready to join in the fantastic music party. After you arrive at the campsite, you can put your tent up. There people talk with each other openly. They are not that cold like those you meet in your everyday life. 

    The festival lasts for four days. During that time you forget all your worries and problems, just like living in a dream. And it is really hard for you to come back to "reality" after that. 

    It seems that Bestival gives people a real sense of unity. I joined in the Bestival with my friends the year before last. It was so happy and we all lost ourselves in the beautiful music. We Are Family sung by Sister Sledge was my favorite. I'm really looking forward to joining in it for a second time.

①它通常在白天爬升至平流层20千米至30千米的高度，将太阳能最大限度地转存到储能电池中，夜晚则逐渐降至15千米至18千米的高度，低速、半滑翔飞行。

②太阳能飞机是以太阳辐射的光能为动力的飞机。

③同时，由于太阳能飞机以太阳能为动力，故其燃油、维护和维修费用基本为零。

④太阳能飞机源源不断的动力，使它一次飞行可长达数月乃至数年。

⑤与常规飞行器相比，太阳能飞机由于不需要传统的化石燃料，因此具有自己独特的优势。

大气中二氧化碳含量与日俱增的原因正确的是（  ）