Question

select the correct answer from each drop - down menu.
in medium - sized stars such as the sun, nuclear fusion almost always means the fusing of nuclei to form, but larger stars can produce elements as heavy as

Explanation:

In medium - sized stars like the Sun, the main nuclear fusion process is the fusion of hydrogen nuclei (through the proton - proton chain reaction) to form helium. Larger stars can go through more advanced nuclear fusion stages (such as the CNO cycle and later stages of stellar evolution) and can produce elements as heavy as iron.

Answer:

First drop - down: hydrogen; Second drop - down: iron