1 53. The fuel source for stars like our sun is A. combustion of chemical fuel B. nuclear fusion of hydrogen C. conversion of gravitational energy D. nuclear energy from uranium 54. One of the isotopes of helium is helium-4, which is comprised of two neutrons and two protons. The correct symbol for this isotope is A. He B. He C. He D. He 55. The stars that live the longest are the _i_stars because they produce energy ii_ The statement above is completed correctly by the information in row Row i ii A. largest (most massive) at a lower temperature B. smallest (least massive) at a lower temperature C. largest (most massive) with less fuel D. smallest (least massive) with less fuel