B. an increase in the overall temperature of the Earth
I say this because the polar ice caps on the poles are melting (which is why the polar bear is now endangered.) and are a result of global warming.
The sailboat being under sail and having less manouverability than the PWC or powered personal water craft has the right of way and should be avoided by the power boat to prevent a collision in case the sailboat has to change direction relative to the wind like tacking.
Its called the Photosphere, which is the part that we can see.
Answer
The Sun spins on its axis in a way similar to the Earth revolving to give us day and night. Also, it 'wobbles' as the planets orbit it, in the same way your washing machine wobbles if the load is unbalanced.
Explanation
hope it helps
