Option A - 'Are,' is incorrect. We can't put a comma here as there is no pause in the sentence. Also, there are no items to separate in the sentence. Thus option A is incorrect.
Option C - We use a semicolon to indicate a pause between two main clauses. As the sentence 'The three highest mountain peaks in the world are' is not the main clause, we can't use a semicolon here. Thus option C is incorrect.
Option D - We use ellipses to indicate incomplete or omitted part of the sentence. As the given sentence is complete, we can't use ellipses here. Thus option D is incorrect.
Option B - We do not need any punctuation after 'are' as the given sentence has no pauses and is in continuation. Thus option B is the correct answer.
'The three highest peaks in the world are Mount Everest, K2, and Kangchenjunga.'