Select all the correct answers. What are three reasons why nebulae contribute more to stellar formation than other regions of the universe? They are rich in hydrogen and helium. They have an unlimited supply of hydrogen. They are far away from black holes. They are dense and hot. They have a strong gravitational pull.

How should the syntax in this sentence be changed, if at all? the scientists spent years analyzing the results of numerous medical studies meant to identify the cause of the disease. no change the scientists spent years looking at the results of a variety of different medical studies meant to locate the cause of the disease. the scientists spent years reviewing medical study results to find the cause of the disease. the scientists spent years studying the results of many medical studies in order to uncover the cause of the disease.