Option 1 states that the North Atlantic Drift keeps the west coast of Northern Europe ice free. This statement is correct. The North Atlantic Drift is a warm ocean current that flows from the Gulf of Mexico across the Atlantic Ocean towards Europe. The warm water from the current helps to moderate the climate in Northern Europe, preventing the coast from freezing over.

Option 2 states that the North Atlantic Drift is responsible for the warm air mass that interacts with the cold air mass from the Polar region and causes rainfall in Western Europe. This statement is also correct. The warm air brought by the North Atlantic Drift interacts with the cold air from the Polar region, creating a temperature gradient that leads to the formation of clouds and precipitation in Western Europe.

Option 3 states that the North Atlantic Drift meets the Labrador current near Vancouver Island and causes dense fog. This statement is incorrect. The North Atlantic Drift does not meet the Labrador current near Vancouver Island. The Labrador current is a cold ocean current that flows southward along the coast of Labrador and Newfoundland, while the North Atlantic Drift flows northeast towards Europe.

Therefore, the correct answer is option 2: I and II only.