the third one that says
evolution of populations over time
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.
Describe<span> how </span>eukaryotic cell's chromosomes change as a cell prepares to divide<span>. Before </span>cell<span> division each </span>chromosome<span> is replicated. At the beginning of division each </span>chromosome<span> has two daughter chromatids. ... A scientist treats </span>cells<span> with a chemical that prevents DNA synthesis.</span>
I can tell you that it is NOT B.
I got it wrong.
Answer: The given statement is true.
Explanation: Ionization energy is defined as the amount of energy required to remove an electron from the outermost shell of an isolated gaseous atom.
General equation of ionization energy is given by:

- If the outermost electron is loosely bound to the nucleus which means that the electron can be easily removed form an atom, it will require less amount of ionization energy.
- And if the outermost electron is tightly bound to the nucleus which means that the electron cannot be removed easily from an atom. And hence, it will require more ionization energy.
Hence, the given statement is true.