Some of the greatest problems we face today are the destruction    of our environment. Brown clouds, polluted water,endangered wild animals.... these problems seem so huge. So my family does what we can. We take cloth bags to stores instead of using plastic bags. We walk where we don't have to drive... But does it do any good? When I am the only one in line at the market with cloth bags, am I doing any good? Does my walking to stores make any real difference to the world? I recently learned something about flamingos  which like to get together in groups of a thousand or more. Every year, when the time comes for migration ,a few of them first take off from the lake.  But none of the others seem to notice. So the small group returns. However, the next day they try again. This time a few more fly along with them, but most of them still pay no attention, so they return again. They try for several times. Every time a few more birds join in but, since thousands of the others still take no notice, the great migration plan is once more stopped. Then one day something changes. The same small group of birds once again starts flying and a small number more join in just as before. then more. Finally, they all take flight and the migration really begins.     What a _ sight it must be -- thousands of flamingos taking off into the sky at once ! A few can make a difference. Even if you're the one to take the first step, and continue trying, others will someday take notice and together we will solve even our greatest problems. What's the writer's purpose of writing this article?
To show that the writer loves to see the migration of flamingos. To tell readers to continue trying and it can make a difference. To introduce a special kind of flamingo to readers. To show that there're many problems in the world.