What connects at least two different high points of hills?

The correct answer is the ridge line because it refers to the natural formation that connects the highest points of different hills or mountains. A ridge line typically runs along the crest of the hills, providing a continuous high point that distinguishes it from other topographical features. This feature is essential in understanding the landscape, as it often influences drainage patterns and can serve as a natural boundary between different geographical areas.

In contrast, other options refer to different geographical characteristics. The valley line usually represents lower areas between two hills, elevation line commonly depicts a constant elevation across a landscape, and base line typically refers to a horizontal line used as a reference point for measuring elevation or land features, rather than connecting high points. Thus, ridge line is the most accurate term for the feature that connects multiple high points.