Final answer:
The correct punctuation mark to use instead of the comma after 'cereal' is a colon, which introduces a list of items or series in the sentence. The correct option is 2.
Step-by-step explanation:
The appropriate punctuation mark to use instead of the comma after the word cereal in the given sentence is a colon. This is because a colon is used to introduce a list or a series, which is the case in this sentence.
For example: Julie went to the store for some groceries: milk, bread, coffee, and cheese. The colon is announcing a list of items that describe the noun "groceries" in more detail.
Therefore, the corrected sentence would read: Three men were major players in the early packaged goods industry: W.K. Kellogg and C.W. Post produced cereal, and King Camp Gillette packaged safety razor blades. The correct option is 2.