Question

____________is the largest cnidoblast.
A. Atrichous isorhiza
B. Holotrichous isorhiza
C. Desmonema
D. Stenotele

Answer 1

Hint: This is a pear shaped structure and occupies the entire space of the cnidoblast in which it lies.

Complete answer:
Cnidoblast is an explosive cell containing one giant secretory organelle called a cnidocyst (also known as a cnida or nematocyst) that can deliver a sting to other organisms. Cnidae are used to capture prey and as a defense against predators. Cnidoblast is also known as cnidocyte or nematocysts commonly known as dinoflagellate. It is distinct from the similar subcellular structures found in the cnidocyte cells of cnidarians, a group of multicellular organisms including jellyfish and corals; such structures are also often called nematocysts.
The stenotele is the largest and most complex nematocyst / cnidoblast. It occupies the entire space of the cnidoblast in which it lies.

Additional information:

Atrichous isorhiza is a type of nematocyst present on the tentacles and helps Hydra to locomote also known as inchmovement or somersaulting.
Holotrichous isorhizas are oval or cylindrical in shape. The thread tube is Hulong with a narrow butt and forms three of four transverse coils. It bears a spiral row of small spines and may coil upon discharge.
Desmonema is a genus of jellyfishes in the family Cyaneidae. Has a ring shaped zone of tentacles.

So, the correct answer is stenotele.

Note: Stenotele (noun; Greek stenos, narrow; telos, the end): (Cnidaria) A stinging nematocyst; a spirally coiled thread armed with spiral rows of projections that is provided at its distal end with a lid (operculum); a penetrant.