D) They can produce chlorophyl on their own.

D) 它们可以自己产生叶绿素。

If you crowd them together like we do in our cultures, you can see their beautiful green chlorophyl.

如果你像我们在我们的文化中那样将它们聚集在一起，你可以看到它们美丽的绿色叶绿素。