Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. Write your answer choices in the spaces where they belong. You can either write the letter of your answer choice or you can copy the sentence. A variety of chipmunk species inhabit western North America. Answer Choices [A]Ecological variation of the Sierra Nevada resulted in the differentiation of chipmunk species. [B]Only one species of chipmunk inhabits eastern North America. [C]Although chipmunk species of the Sierra Nevada have the ability to live at various elevations, each species inhabits a specifically restricted one. [D]Chipmunks aggressively defend their habitats from invasion by other species of chipmunks. [E]Experimental studies indicate that sagebrush chipmunks live in the desert because of their physiological requirements. [F]The most aggressive of the chipmunk species is the lodgepole chipmunk. The author asks the question 'Are they really that smart?' for which of the following reasons?