Question

add a comma, semicolon, or colon if needed. otherwise, submit the text without any additional punctuation. mr. khan has hiked six of earths most magnificent mountain ranges the great dividing range, the andes, the himalayas, the atlas mountains, the alps, and the rocky mountains.

Explanation:

The part after the blank is a list that elaborates on the "six of earth's most magnificent mountain ranges" mentioned before. A colon is used to introduce a list or an explanation that follows a statement, so a colon should be added here.

Answer:

Mr. Khan has hiked six of earth's most magnificent mountain ranges: the Great Dividing Range, the Andes, the Himalayas, the Atlas Mountains, the Alps, and the Rocky Mountains.