It provides the reader with your topic and give them a central idea of your writing.
Small leaves duh and I know because I study it
Answer:
Cells, Tissues, Organs, Organism
I hope this helps!
I just had this answer but it hasn't been graded. I put 1. Meteor impacts, 2. volcanic gases and 5. Milankovitch cycles. I didn't put earthquakes because I wouldn't think it would affect the climate changing since they just affect ground movement.