The correct option is C Hertwig
In 1875, Oscar Hertwig discovered and described the fusion of sperm and egg nuclei (fertilisation) in sea urchins.
Charles Bonnet discovered parthenogenesis in aphids. It is the process in which the female gametes give rise to a new offspring without fertilisation. No male gamete is involved in this process. It is a kind of an asexual reproduction. The offspring produced are identical to each other and to their parents, both morphologically and genetically.
Nawaschin discovered double fertilisation in plants for the first time. In the case of sexually reproducing plants, two male gametes are formed. One of the male gametes fuses with the egg and produces a diploid zygote. The other male gamete fuses with two haploid polar nuclei and produces a triploid endosperm. The two events are collectively referred to as double fertilisation.
Robert Hooke observed cells (dead cork cells) for the first time.