Answer:
Option D, Geosphere
Explanation:
Geosphere is the of earth which comprises of various rock forms, geological process , rocky structures and all earthy components and processes that have shaped the present land form of this planet. Hence, earth's geosphere also comprises of both volcanoes and earthquakes. Therefore , the scientist must study the geosphere of earth.
Earth's atmosphere comprises of all gases and air.
Earth's biosphere comprises all living component on this planet
Earth's cyrosphere comprises of frozen water regions
Thus, option D is correct
