The correct answer is D. Extract, Transform, Load.
ETL is a three-step process for loading data into a data warehouse. The first step is to extract data from the source systems. The second step is to transform the data into a format that can be loaded into the data warehouse. The third step is to load the data into the data warehouse.
Option A is incorrect because it does not include the step of loading the data into the data warehouse.
Option B is incorrect because it does not include the step of transforming the data.
Option C is incorrect because it does not include the step of extracting the data.