by No Name Given
Editor:
Good question, you made me look it up to confirm my guess. The best choice from the samples you give below is number 3.
Use the colon to introduce the list. Then, since items on the list do not conform to one pattern, use the semicolon as a "super comma" to distinguish the list within a list.
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Travis made a list of things to do: call-home, buy eggs, bread, and milk, and return library books.
Travis made a list of things to do; call home, buy eggs, bread, and milk, and return library books.
• Travis made a list of things to do: call home; buy eggs, bread, and milk; and return library books.
Travis made a list of things to do: call home, buy eggs, bread, and milk, and return library books.