(The answer is at the bottom)
A) Medical studies have proven that sun damage can lead to melanoma; however, you should always wear sunscreen to protect your skin from those damaging ultra-voilet rays.
It's pretty much starting another sentence however isn't the best choice.
B) Medical studies have proven that sun damage can lead to melanoma; finally, you should always wear sunscreen to protect your skin from those damaging ultra-violet rays.
"Finally" is the words of chronological order, and this is sentence is not in chronological order.
C) Medical studies have proven that sun damage can lead to melanoma; therefore, you should always wear sunscreen to protect your skin from those damaging ultra-violet rays.
this makes the most sense and fills in the blank correctly. It fits with the way the sentence is arranged.
D) Medical studies have proven that sun damage can lead to melanoma; for example, you should always wear sunscreen to protect your skin from those damaging ultra-violet rays.
this doesn't even fit the sentence. It makes NO sense.
C is the BEST answer.
