D. Neither light nor moisture is good for food preservation, so most food products are packaged immediately after they are processed.
Explanation:
A comma shows a break or pause in a sentence. A comma is used to separate independent clauses therefore it can be said that the first and second half of the sentence in question can be said as two different sentences.
A comma brings together two phrases or clauses. It is a useful punctuation mark which is used to indicate to readers a certain separation of words, phrases, clauses or ideas in order to prevent misreading or misunderstanding what the writer intended to say. It is important to know where exactly in a sentence to insert a comma so you can convey the meaning of your sentence perfectly.
