Select the option that can be used as a one-word substitute for the given group of words.
A study of the conditions and structure of the earth

* Geology: The science that deals with the earth's physical structure and substance, its history, and the processes that act on it.
Geography: The study of the physical features of the earth and its atmosphere, and of human activity as it affects and is affected by these.

Meteorology: The branch of science concerned with the processes and phenomena of the atmosphere, especially as a means of forecasting the weather.

Biology: The study of living organisms.