"Leave as is" is the most effective substitute for each underlined part of the sentence.
D . Leave as is.
Explanation:
It is meant to be as it is because comma is the right punctuation that denotes the meaning of the sentence, whereas colon and semi - colon shows the differences and levels of the two words where as comma denotes the action of the person. A semicolon is most regularly used to connect two autonomous statements that are firmly related in thought. At the point when a semicolon is utilized to join at least two thoughts (parts) in a sentence, those thoughts are then given equivalent position or rank.