A.造孢細(xì)胞→孢原細(xì)胞→花粉母細(xì)胞→小孢子B.花粉母細(xì)胞→孢原細(xì)胞→造孢細(xì)胞→小孢子C.孢原細(xì)胞→花粉母細(xì)胞→造孢細(xì)胞→小孢子D.孢原細(xì)胞→造孢細(xì)胞→花粉母細(xì)胞→小孢子