Final answer:
The westerlies impact the climate of Western Europe, primarily due to the moderating influence of the warm Gulf Stream which leads to a type C climate in that region. This makes option (a) correct.
Step-by-step explanation:
The westerlies are prevailing winds that originate from the west and affect climate patterns significantly. These winds impact the climate of Western Europe, which is characterized by a moderate type C climate, largely due to the influence of the Gulf Stream. The Gulf Stream originates in the Gulf of Mexico and transports warm water across the Atlantic Ocean to Western Europe. This ocean current has a profound effect on the region's climate, moderating temperatures and allowing for milder weather conditions, even in areas at northern latitudes, such as the western coastal islands of Scotland.
Furthermore, Eastern Europe tends to experience colder type D climates due to its interior location and greater distance from the moderating effects of the Gulf Stream and other bodies of water. In contrast, Western Europe benefits from the moderate maritime influences. Therefore, the answer to the student's question is that the westerlies impact the climate of Western Europe, making option (a) the correct choice.