从降低成本和减少环境污染的角度考虑，制取硝酸铜最好的方法是（　　）

阅读材料，回答问题．

青藏高原有一种叫蝙蝠蛾的昆虫和一种虫草菌．在蛾幼虫冬眠时，虫草菌的孢子会随风飘到幼虫体表，并钻入 幼虫体内，吸收幼虫体内的营养而快速繁殖．菌丝在虫体内经过几个月的慢慢成长，充满虫体，幼虫只剩外骨骼，就是“冬虫”．隔年夏季，菌丝体会从死亡虫体的 头部长出，像草一般，称为“夏草”．这就是冬虫夏草的名字的来源．

阅读下面短文，掌握其大意，然后从各题所给的四个选项（A、B、C和D）中，选出最佳选项。

    I never thought I would be a “runner”. I was the girl who 1 slowest in the PE class. A few years ago, I was walking with a group of 2  in the Race for the Cure, a 5km race designed to 3 money for the fight against breast cancer(癌), 4  one lady caught my 5 .

    She was one of the weakest-looking women I've ever seen. She must have been close to seventy years old, 6  a T-shirt with the word “Survivor”. She was so small that it seemed as if she could even be 7  by a strong wind. But, she was running. And she was 8  me and my group of friends. She ran slowly, but 9  —as if each step pushed her cancer further into her past. Right at that moment, I10  that in the next Race for the Cure, I'd be running along with her.

    A week later, I found myself in the 11 , running on the treadmill(跑步机). Three minutes after I started, my face was bright red. I felt like my lungs were going to burst. I 12  slow down to a walk. I thought of the 13  at the race. I kept it up. I was able to go a little 14  each time. Three and a half minutes. Four minutes. Five.

    A year later, I was 15  at the Race for the Cure, but this time, I 16  with the runners. When the race started, the other runners passed me by. I ran forward. I wondered if I'd be 17  to do it. But then, I remembered the brave woman. I ran as fast as I could until I finally crossed that finish line. I had just 18  my first race! I 19  down at my legs, amazed. They had done something I'd never thought 20 . I have never felt stronger than at that moment. And, I knew that I wanted to do it again.