Given land/water heating contrasts, one would expect to find the coldest winter temperatures in the northern hemisphere
a) near the north pole.
b) in siberia (70°n).
c) in southern canada (50°n).
d) in oklahoma (35°n).
e) over the oceans off of alaska.

a) near the North Pole

Explanation:

As our Earth has a little bit inclination, the heat from the sun it does not reach the same to all the planet´s surface. That is one reason, why we have the imaginary lines that are called, latitudes, there are lines that start from the equator until the north pole, and in the center or our planet at 0 °, is the hottest temperatures, but as moving to the north, the degrees of the latitude, start to increase, in this way, the temperature will decrease. This relation ship is inverse proportional, as we increase the latitude, the temperature will decrease. In the examples that we have, the North Pole has 90° so is the highest latitude, so it will present the lowest temperature.

Hope this info is useful.