Answer:
Proximity to the ocean
Step-by-step explanation:
Ocean City, MD, has a milder climate than Deep Creek Lake, MD, because Ocean City is a coastal city in front of the ocean, and the ocean always moderates the climate.
Deep Creek Lake, MD, is located in the mountains of Maryland, in the eastern edge of Appalachia. Because of this, it has a much more continental climate, meaning that summers are hotter, and winters are colder.