@prestonbigley759 thanks!

@benedicthcp640 thank you great explanation!

@AccountsPlayable Thank you so much! This answers my confusion. What I was thinking is that people's old belief was false -> how could a historical phenomenon (people used to believe that earth is important) is "false" since it has, factually, existed? I chose (a), but even following my logic above, (a) still doesn't add up because the idea that "earth is important" is true.