Answer:
The term hippocampus is related to brain research because the hippocampus is the part of the brain that contains memories, emotions and learning.
I don't know the second part, sorry-
<span>Which of the following words best characterizes Mary Warren? gullible.</span>
I think, it explores nature and captures the essence of the moment.
<span>As periods in mathematics we call groupings of large numbers (three-digits) usually separated by comma or space.
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In this particular case we got two periods: 913 and 256.
Digits 913 are in the thousands period, while 256 in the units period.