Although I am not 100% (i am not the best for geography), It must be D. Hope this helps your grade! :3
I think that this is something you should, as the assignment states, "conduct independent research". meaning, this is something you have to do AT LEAST 90% yourself. my suggestion: start by googling 'yellowstone eruption' and go from there. I just don't want you to be in trouble with your teacher because you plagarizing.
Answer:
<h2>Upper epidermis.</h2>
<em><u>H</u></em><em><u>o</u></em><em><u>p</u></em><em><u>e</u></em><em><u> </u></em><em><u>t</u></em><em><u>h</u></em><em><u>e</u></em><em><u> </u></em><em><u>a</u></em><em><u>n</u></em><em><u>s</u></em><em><u>w</u></em><em><u>e</u></em><em><u>r</u></em><em><u> </u></em><em><u>h</u></em><em><u>e</u></em><em><u>l</u></em><em><u>p</u></em><em><u>s</u></em><em><u> </u></em><em><u>u</u></em><em><u>.</u></em><em><u>.</u></em><em><u>.</u></em><em><u>.</u></em>
The answer is the endogenous opiate.
The human body naturally produces its own opiates like substances and uses them as neurotransmitters. These substances include endorphins, enkephalins, and dynorphin, often collectively known as endogenous opioids. Endogenous opioids modulate our reactions to painful stimuli.
The situation is an exponential growth wherein an example is on population when as the population gets larger, it grows more quickly.