Explanation: Class Cephalopoda are highly advanced and organized group of marine animals that have a distinctive characteristics of their head been attached to their body and they possess tentacles that is to say their head is completely merged with their foot with their arms or tentacles surrounding the head.
Their body plan includes the head, two eyes, a mantle, a siphon and a minimum of eight arms. Some examples are octopus, squid and the cuttlefish
The correct answer is the evolution of multicellular life. The evolution of multicellular was the most important event happened during the creation of the ozone layer. All of type of the organisms had evolved over time.
