Question

Day after day , the earth made _ year-long journey around the sun

Answer 1

B or d i think is the right answer

God Bless

Answer 2

Day after day, the earth made its year-long journey around the sun.

His would be if you were referring to a male (animal, human, etc).
It's <em /><em />shows possession of something, the earth doesn't possess the year-long journey.
Its' is another way of showing possession if the thing that posses it already has an s on the end. (Example: Charles' car.)
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