When I arrived in Beijing more than five years ago, I had already given blood 79 times. I wanted to continue to be a donor (献血者). But entering a Red Cross clinic (诊所) in Beijing, I was surprised to be received as a hero. For me, a blood donation was simply a good habit and gift of love to humans.
In Canada, donors can give 450 ml each time, every 51 days. That means six times a year. in China, we can give only 200 ml, every four months.
In 1984, there were only 19 donors in Beijing who offered their blood for free. One year later, there were 141. In 1986, 1 083, and so on until the figure reached 10 046 in 1990, 14 016 in 1992 and more than double that the following year. There were 41 037 in 1994, and my statistics stop here. I’m so glad to see that the Chinese have understood that giving blood is not erous, and that it’s a way to say, in a real communist spirit, "Brother, I love you".
In fact, every time I give blood, I think of my blood running in a man or a woman’s veins (血管). Through donation thir Chinese have become my relatives now. Giving blood is like giving birth. Some of these thir people may have died without my donation; doesn’t that make it worth becoming a volunteer (志愿者) What makes me even happier is when I can convince a Chinese friend to come with me and become a donor too.
Things have become easier since May 1, 1996. A Hong Kong donor offered a well-equipped mobile unit to the Red Cross here. The vehicle stands in front of the Xidan Shopping Mall every Wednesday and Sunday morning, from May to the end of October. Donors just need a few minutes. I hope this public example will encourage new donors, and blood donation will become a social trend among the population.According to the writer, more and more Chinese are giving blood free because（）

A．they know the advantage of blood donation
B．they have learned how to donate blood
C．they have realized its great significance
D．they know it's a way to show their generosity