Answer: Commensalism
Explanation: Well you can already eliminate parasitism because that is when an organism leeches off another. Mutualism is when one organism needs to depend on another compared to A where both are benefited. Then you can eliminate d because competition is when two organism compete with each other for survival not benefiting them both.
The Role of blastula is Blastula is this and that and Yh they should gather everyday to stage the Animals
The feather fell slower because it encountered more air resistance.