Question

read the beginning of emilys report. it is hard to comprehend the size of the sun. one way to understand its size is to imagine that the entire solar system is a play on a theater stage. the sun can be thought of as the \leading actor\ in the solar system, and the planets as the \supporting actors.\ earth, for example, is only a small part of the solar system, even though our planet is home to immense cities such as tokyo, new york city, mexico city, and beijing. earth has a diameter only 1/109th the diameter of the sun! returning to the analogy of the solar system as actors on a stage, the sun would fill the stage. earth would be a tiny dot, barely visible in the brilliance of the plays star—the sun. the sun is the center of our solar system, but scientists consider the sun to be a very average star. nevertheless, the sun and its role in the solar system is the focus of much scientific research in a field known as heliophysics. nasa has a program called the science mission directorates heliophysics research program. one of the programs biggest challenges is \to explore the full system of complex interactions that characterize the relationship of the sun with the solar system.\ this research may help scientists more fully understand how the sun influences earths environment and how it affects all the life on earth that relies on energy from the sun for its existence. emily is creating a bibliography for her report. which sentence from her report needs to have its source included in her bibliography? 1. the sun can be thought of as the \leading actor\ in the solar system, and the planets are the \supporting actors.\ 2. earth, for example, is only a small part of the solar system, even though our planet is home to immense cities such as tokyo, new york city, mexico city, and beijing. 3. the sun is the center of our solar system, but scientists consider the sun to be a very average star. 4. one of the programs biggest challenges is \to explore the full system of complex interactions that characterize the relationship of the sun with the solar system.\

Explanation:

Sentences 1 - 3 are general - knowledge statements about the solar system. Sentence 4 quotes a specific challenge of a NASA program, which is a specific piece of information from a particular source and needs to be cited.

Answer:

1. One of the program's biggest challenges is "to explore the full system of complex interactions that characterize the relationship of the Sun with the solar system."