Answer:
The correct answer is option b. "Alpha eventually replaced by theta".
Explanation:
Electroencephalogram (EEG) techniques allows researchers to monitor the phases of sleeping according of what brain waves are seen in the equipment. A normal adult connected to EEG will respond with alpha waves during a wakeful state. However, as the person becomes drowsy and enters to the first stage of sleep, the alpha waves will be eventually replaced by theta waves. Theta waves are the dominant waves during sleeping, and also could be seen during deep meditation.
Natural disasters weaken a community's social infrastructure because
D. Natural disasters can cause billions of dollars in property damage<span>.
The social infrastructure of a community includes social assets such as schools, hospitals, prisons and community housing. Such places are damaged in natural disaster, adversely affecting the community.</span>
The increased temperature melts glaciers, ice caps etc. and thus increases the sea levels
I believe the correct answer is A) Silurian period occurred before the Neogene era, because the other answer are wrong.
Hadean eon ended before Silurian period.
Mesozoic and Permian era were after Silurian period.
