There are only two main types of physical weathering:<span>Freeze-thaw occurs when water continually seeps into cracks, freezes and expands, eventually breaking the rock apart.</span><span><span>
</span></span><span><span>Exfoliation occurs as cracks develop parallel to the land surface a consequence of the reduction in pressure during uplift and erosion.</span></span>
ANSWER:
<u><em>The source of sunlight is the main source of energy and if there will be more sea weed trapping sunlight then there will be a competition between seaweed and coral reef. So, the natural reason for the decreased biodiversity is an overgrowth of the seaweed population which prevents the light from reaching the reef.
</em></u>
<u><em /></u>
4 is nucleus because it’s in the middle
According to the chart answer must be a