C. They are pulled toward Earth by the force of gravity (and in Physics you would learn that the deceleration speed of gravity is -9.8m/s/s)
Invasive species or environment
I think its d the plante kingdom
After four divisions, the zygote becomes a morula- the stadium that consists of 16 blastomeres. By the fifth day of development the form of the blastocyst is formed through the processes of compaction, cell division, and blastulation. Later, specialized cells in the embryo are derived from the inner cell mass (ICM) of the blastocyst.
