Answer:
Option D, are formed by stellar nucleosynthesis during the life cycles of existing stars.
Step-by-step explanation:
The light weight elements such as hydrogen, helium, lithium etc were formed during the Big Bang nucleosynthesis.
Later on further evolutions started in stellar object and stars that were heavier than sun underwent reactions in succesive stages of stellar evolution that converted light weight elements such as helium into carbon and oxygen. However, in more massive stars , elements like silicon and iron were produced.
Hence, option D is correct