Question

what was the ratio of hydrogen atoms to helium atoms when nuclear fusion stopped? 25% hydrogen to 75% helium 75% hydrogen to 25% helium 33% hydrogen to 66% helium 66% hydrogen to 33% helium rewatch

Explanation:

In the context of nuclear fusion (related to astrophysics, a subfield of Physics in Natural Science), when nuclear fusion stopped in the early universe (or in stars' evolution context), the ratio of Hydrogen to Helium atoms was approximately 75% Hydrogen and 25% Helium. This is a known scientific fact about the primordial abundance of these elements from Big Bang nucleosynthesis or stellar fusion stopping scenarios.

Answer:

B. 75% Hydrogen to 25% Helium (assuming the second option is labeled as B; if the original options had different labels, adjust accordingly. Based on the standard knowledge, the correct ratio is 75% H to 25% He, so the option with "75% Hydrogen to 25% Helium" is the correct one.)