<span>The answer is A. high pressure. The fusion of two deuterium nuclei can only be done with high temperature and also highpressure to prevent electrostatic repulsion of the proton. The successful combination of the deuterium then creates helium as it all combines.
Source: Objective Pre-Engineering Physics, Objective Questions with a Glossary of Knowledge wrote by Shobhana Sharma/ Google books </span>
The primary consumer in the food chain is the bottom level of animals that eat plants and grasses for nutrition.
FOR EXAMPLE: grasshopper
Garstang's Auricularia hypothesis suggests that ancestral vertebrates may have evolved from urochordate larvae.
What is Garstang's Auricularia?
The auricularia hypothesis, proposed by Garstang was an attempt to explain how the chordate body plan originated from a deuterostome common ancestor by emphasizing the significance of changes in larval forms. According to the Garstang Hypothesis, development of sexual maturity in a non-metamorphosing lineage of tunicates might provide the immediate proto-chordate ancestors of more typical chordates.
Learn more about Garstang's Auricularia here:
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The correct answer is - D) covered by warm shallow seas.
The fact that the crinoids are have an abundance in the fossil records in Pennsylvania in the Mississippian Period, tells us that this area was covered with shallow and warm seas. The reason why we can get that conclusion is that the crinoids live only in that kind of environment, so it simply a logical conclusion.
The geological data is also confirming this, as it is easily noticeable in the layers that during this period of the geologic past, what is now Pennsylvania, was covered with shallow sea waters. Also, this waters were warm too, as the climate was warm and humid and that period, so it was a perfect environment for the crinoids to flourish.
