If Average Temperatures from South Dakota Were Compared to Temperatures

If average temperatures from South Dakota were compared to temperatures from Oregon it would show that Oregon has warmer winters and cooler summers than South Dakota does.What accounts for why this is when they are at similar latitudes?

A) South Dakota has fewer trees.
B) The Pacific ocean makes Oregon temperatures more moderate.
C) Oregon receives more rainfall.
D) South Dakota has fewer lakes and rivers.
E) South Dakota has more prevailing winds from the west.