Explanation:
1] ADAPTATION : WE HAVE BEEN ADAPTING A DOG AS A PET.
2] BIODIVERSITY : BIODIVERSITY IS THE VARIABILITY AMONG LIVING ORGANISMS FROM ALL SOURCES INCLUDING TERRESTRIAL, MARINE, AND OTHER AQUATIC ANIMALS
3] ISOLATION : THE PROCESS OR FACT OF ISOLATING OR BEING ISOLATED
4] VARIATION : DIFFERENCE BETWEEN ORGANISMS OR PLANTS
SO, THIS IS YOUR ANSWER
Answer: b. Muscles
A metazoa is a division of animal kingdom that includes all animals expect protozoa and sponges. Metazoa division includes multicelluar animals, which exhibit highly differentiated cells. They have muscular and nerve system and well coordinated tissues and organs. Locomotion requires a coordination activity of muscular, skeletal and neural system. It is mainly achieved by contraction and relaxation of muscles that occurs due to specialized muscle proteins named as actin and myosin which receives signals from nerves.
Hence, locomotion in metazoa is due to contraction of muscles.
