Lenses for Sunglasses

So I'm looking to buy some sunglasses (Oakleys) and I was wondering if anyone could point in the direct direction on what type of lenses to buy. I have a choice to choose betweendark lenses, transition lenses, or plain clear lenses with my prescription, but I have no idea what each one would look like and what purpose they would serve.

Can anyone please tell me the differences+pros/cons between these types of lenses? I already have an idea of what transitions lenses are.

 

Can't you talk to your optician about it? They'll know which would suit your needs best by (I'm guessing) asking about what you do on a normal day.

 

I wish...but I'm actually buying them online via Amazon, and I am only in contact with the company that is selling these glasses via email. =/