73%
Explanation
Understanding the Question The question asks us to identify the percentage of dark energy in the universe from the given options.
Identifying Dark Energy Percentage Based on current cosmological models, dark energy makes up approximately 73% of the universe.
Selecting the Correct Answer Therefore, the correct answer is B. 73%
Examples
Understanding the composition of the universe, including the percentage of dark energy, helps scientists model the universe's expansion and predict its future. For example, knowing that dark energy constitutes about 73% of the universe allows researchers to refine cosmological models and understand the accelerating expansion of the universe. This knowledge is crucial in astrophysics and cosmology for studying the large-scale structure and evolution of the cosmos.