Answer :
The question is asking us "Which of the following geographical features most affects the dry climate of Chile?" and the answer is the mountains. We can immediately reject the options of "Atlantic Ocean" and "rain forest" as they are not present in Chine - Chile is bordering the pacific ocean. It is a very mountaneous country, so "mountains" are the best answer.
The correct answer is - A. Mountains.
Chile is country located on the western coast of the South American continent. It is a thin but long country, kind of snake-shaped, and it is bordered by the Pacific Ocean on one side, and the Andean Mountain Range on the other side.
The Andes are a very important climatic factor for Chile, because they stop the warm air masses from inside the continent to penetrate to Chile, and also contribute to the accumulation of cold and dry air masses coming from south. These cold and dry air masses are coming with the cold ocean currents from the Antarctica, and they do not bring in rain in Chile, which makes the country pretty dry in general. In fact, Chile has the driest place in the world in its territory, the Atacama Desert.