The Sun and other stars are powered by nuclear fusion reactions, in which two atoms collide to form a single heavier atom, releasing energy. Scientists have long believed _______ fusion has the potential to meet humanity's clean energy needs. \(\underline{\phantom{\rule{0.0pt}{0.8em}}}\)<br/><br/>Which choice completes the text so that it conforms to the conventions of Standard English?
MM
Mashaal Masha
Jan 15, 2024
The Sun and other stars are powered by nuclear fusion reactions, in which two atoms collide to form a single heavier atom, releasing energy. Scientists have long believed that fusion has the potential to meet humanity's clean energy needs. _______ prior to December 2022, no fusion reaction in a laboratory setting had ever generated a net energy gain.
Which choice completes the text with the most logical transition?