To complete a paragraph, understand the overall theme and flow of ideas of the paragraph and focus on the last line. Here, the theme is that hydrogen will be an important part of our future. The last line talks of the results of the McKinsey study on the increasing use of hydrogen in the future. So, the logical extension of the paragraph is to expand on the same theme. The last line says ‘18% of global energy consumption and reduce carbon dioxide emissions from current levels by some 6 gigatons’. And the next line would logically talk about the effect of this change.
Option E looks correct but the tense is different and the general population’s awareness of the importance of hydrogen is out of scope of the passage.
Hence, B is the correct answer.