The germinal layers that give rise to the digestive system is Ectoderm, Endoderm, Mesoderm, Respectively. And the best answer among your choices is the last option which is C. I hope you are satisfied with my answer and feel free to ask for more
Answer: C. The environment changed suddenly from a shallow ocean setting to a river system.
Explanation:
The presence of the fossils of shallow oceanic creatures like corals points to the fact that the environment was a shallow ocean at some point. There is also a presence of a layer on top of that which points to a river system.
The fact that the oceanic fossils are beneath the river system layer means that the ocean came first and the river system layer came second. The environment must therefore have been a shallow ocean setting that changed into a river system.
The allele for blue flowers is dominate. If the blue and yellow were both homozygous (either FF or ff), and the blue is the only one that showed up (meaning it overpowered the yellow) shows that it is the dominate allele.