OG11-P387-121题，解释中的C选项，对于生化问题不太懂

dreamermm

how can these cells differentiate and form structures (the development of a plant's cells)? the answer is that only a small subset of the genes in a particualr kind of cell are expressed, or turned on (controlling the expression fo the cells' genes) at a given time.this is accomplished by a compex of system of chemical messengers.(five hormones + oligosaccharins) 

我主要从开头的这几句话里分析.

再看文章的结构, 第一段, 指出oligosaccharins也是regularoty molecules (line 13), 后面几段围绕olgosaccharins的功能展开, 第二段, 写oligosaccharins与five hormones的不同, 第三段, 和动物进行对比, 描述a hierarchy of hormones,第三段, 写oligasaccharins的特点和其在hierarchy中的位置.

以上是我的理解.