What dropdown option should be selected: Monthly without discount or Yearly with 50% OFF?

I offer web services such as hosting.

In a <select> field, wich option should be pre-selected? 1 month (without discount), or 12 months (50% off)?

The question might seem kinda obvious, the 12 months should be better - but what if the buyer don't want a whole year with the product, and feel bad for paying it's full price, knowing it could be cheaper, and end up giving up on the purchase?

What do you guys think?