Ctenoplana and Beroe exhibit biradial symmetry and lack cnidoblasts. Cnidoblasts are specialized cells used by some organisms, like jellyfish, to capture prey.
So, the correct option is (B): Ctenoplana and Beroe
Human Respiratory System is a compound biological system of organs and tissues that helps in gaseous exchange. The system includes airways, lungs, and blood vessels. Its core function is to introduce oxygen and expel carbon dioxide from the body. The atmospheric air is continuously pumped in and out through a system of pipes which are called the conducting airways. There are a great number of muscles and blood vessels involved in the whole process of respiration.
