The correct answer is A. Crust
Step-by-step explanation:
The Earth is composed of different layers this includes the inner core that is the deeper layer and it is divided into the inner and outer core, the mantle that is the thickest layer and the crust that is the outer layer of Earth. In the case of the crust, this is divided into the continental crust and the oceanic crust. Additionally, it is the crust the layer we know more about as this includes the soil, rocks, trees, mountains, etc. in the Earth. This also implies it is the crust the layer most living things live and interact this includes animals, plants, fungi, bacteria, etc. as organisms are not commonly found in deeper layers.