Double fertilization is the characteristics of
a. Funaria
b. Pteris
c. Capsella
d. Cycas

Hint: Double fertilization in plants is a complex fertilization mechanism. In this process of double fertilization, one female gamete (megagametophyte or embryo sac) fuses with two male gametes (sperm). Some plants have chances to form polyploid nuclei. Double fertilization forms one diploid cell and one triploid cell. The diploid zygote cleaves and produces an embryo. The triploid cell forms an endosperm that provides nourishment to the developing embryo.

Complete answer:
• Double fertilization occurs in Capsella.
• Double fertilization in plants was discovered by Nawaschin in 1898.
• Double fertilization is a process where a triploid endosperm and a diploid zygote is produced.
• When secondary polar nuclei and a male gamete fuse, it results in the formation of the triploid endosperm.
• When a haploid egg cell and a haploid male gamete fuse, a diploid zygote is formed.
• Funaria is a monoecious plant.
• Pteris reproduces by vegetative an asexual mode.
• In Cycas fertilization is through zooidogamy and siphonogamy.

Hence, the correct answer is option (C).

Additional information:
• Gymnosperms lack double fertilization.
• In double fertilization, the plant doesn't need to give energy in seed nutritive tissue till after an egg is fertilized.
• The endosperm nucleus is very active and cleaves rapidly; it produces the nutritive tissue rapidly.
• It uses both the male gametes formed by the pollen grains.

Note: Double fertilization is the joining of one female gamete with two male gametes. One male gamete joins with the female egg to form a zygote whereas another male gamete joins with two polar nuclei to give rise to triploid endosperm form.