(a) (b) Letter "A" represents pollen grain that reaches stigma (B) through the process of pollination. Germination of pollen grain forms pollen tube that reaches egg cell through ''D'' (c) Pollen grain germination is attachment of pollen to stigma of flower and formation of pollen tube. Letter "C" refers to pollen tube that carries male gametes to ovule for fertilization. (d) Event of double fertilization and subsequent growth and development results in development of ovule into seed. Each seed contains a young plant embryo (developed from zygote) and nutritive tissue (the endosperm), both of which are surrounded by a protective seed coat (derived from integument). During development of seed from an ovule following fertilization, the ovary wall surrounding it enlarges and develops into a fruit wall while ovary makes fruit.