The correct answer is option 3: Ecology. Ecology is the branch of science that deals with the interactions between living organisms and their non-living environment. It focuses on studying how organisms interact with each other and with their surroundings. Ecology can be further divided into different sub-disciplines, such as autecology and synecology. Autecology, which corresponds to option 1, is the study of individual organisms and their interactions with the environment. Synecology, which corresponds to option 2, is the study of communities of organisms and their interactions within a specific environment. Therefore, while autecology and synecology are related to the study of interactions in ecology, they are more specific sub-disciplines, while ecology as a whole encompasses the interactions of all living organisms with their non-living environment.