Why isn't england as cold as ne canada, even though they are found at the same latitude?

North East Canada is comparatively colder than England even though they lies on the same latitudes because the westerlies directly affect the places in England. In addition to that, the ocean brings in warm current towards England.  

Westerlies are the wind blowing in the mid-latitudes from the western direction towards the eastern direction in both the hemisphere. It originates at the 30° latitudes due to the region of high-pressure and flows towards the higher areas of 60° latitude.

Since England and North East Canada, both are located between the latitude of 30° to 60° in the northern hemisphere, so it experiences the strong westerly winds.

As this wind comes from the tropical region so they bring warmer air currents often accompanied by rainfall. This wind when reaches England, the ice present there gets melted. So the temperature is relatively warm in England. But these winds have little effect on NE Canada, so they remain cold.

well, that's easy; the answer's c, "it reduces contamination of the water and substrate of the estuary."