Complex sentence: Only summits with a sufficient degree of prominence are regarded as independent mountains, for example, the world's second-highest mountain is K2 (height 8,611 m, prominence 4,017 m).
Split into simpler sentences: Only summits with a sufficient degree of prominence are regarded as independent mountains. For example, the world's second-highest mountain is K2 (height 8,611 m, prominence 4,017 m).