to help astronauts breathe in outer space to help with the weight of astronauts during space walks to manage carbon dioxide that astronauts breathe out to mix with the thin atmosphere for astronauts during space walks
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Why do astronauts need oxygen in the backpacks of their spacesuits?
Possibilities:
- to help astronauts breathe in outer space
- to help with the weight of astronauts during space walks
- to manage carbon dioxide that astronauts breathe out
- to mix with the thin atmosphere for astronauts during space walks

to help astronauts breathe in outer space