The sun is expected to exhaust its hydrogen fuel in about 5 billion years. What will be its effect?

A. The sun will then expand into a red giant and possibly swallow the outer planets
B. The sun will then expand into a red giant and possibly swallow the inner as well as outer planets, including Earth
C. The sun will then expand into a red giant and possibly swallow the inner planets, including Earth
D. Sun will stay as it is