How are homologous structures such as forelimbs evidence for common ancestry and change over time?

What is the significance of the protein-lined pits? a. protein attracts other proteins needed for atp synthesis within the cell. b. protein-lined pits are able to transport one molecule at a time down the concentration gradient within the cell. c. the polarity of proteins allows other polar molecules to attach and be transported in the cell by transport channels. d. receptors within the pits allow ligands to fuse and be transported into the cell by endocytosis.

Why does the earth spin slowly, not faster? is it possible to prove it scientifically? can you prove it with math?

Which force diagram accurately represents a satellite in orbit around earth? image for option 1 image for option 2 image for option 3 image for option 4