Oxygen is transported in the blood in two ways: A small amount of O 2 (1.5 percent) is carried in the plasma as a dissolved gas. Most oxygen (98.5 percent) carried in the blood is bound to the protein hemoglobin in red blood cells. A fully saturated oxyhemoglobin (HbO 2) has four O 2 molecules attached.
(https://www.cliffsnotes.com/study-guides/anatomy-and-physiology/the-respiratory-system/gas-transport)
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.
The answer is c because they are categorized as they come in order
Hydrogen sulfide gas
Volcanic gases are gases from volcanoes. These are gases trapped in the spaces between volcanic rocks. The sources of this gases are the recycled constituents of the earth mantle, assimilated constituent of earth crust and groundwater, earth atmosphere. The principal component of volcanic gases are water vapor, carbon dioxide, sulfur dioxide , hydrogen sulfide. Gases varies depending on the volcano, water vapor is the most common among the gases.
