A reef than surrounds a volcanic island is an : Atoll
Atoll usually takes shapes in a form of ring that surround the areas of volcanic island that consist of corals. It usually only exist in warm waters, so volcanic islands will provide perfect environment for the corals
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<span>Mercury's distance at inferior conjunction is 0.61 AU
Looking at a table of orbits, Mercury has an orbital distance of 0.39 AU. So the inferior conjunction will be:
1 AU - 0.39 AU = 0.61 AU</span>
Transform/conservative plate boundary.
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The answer is b I believe so