Gnathostomes are jawed vertebrates, so they have jaws.
The main function of the nematocyst is prey capture. The correct option among all the options given in the question is option "B". The nematocysts are used by Cnidarians like hydra, jellyfish etc. It is actually a specialized capsule that contains venom and it is used to paralyze and capture small preys for food and also to sting any enemy that comes near.
Answer:
A gene is a section of a double-stranded molecule known as DNA. This molecule is found within the nucleus of the cell, contained in threadlike structures called chromatin. The two strands form a double helix linked by a series of paired bases. The base adenine is always linked to thymine and the base cytosine is always linked to guanine.