Comma to end a series and set it off from the rest of a sentence

Question

The following is a question from the ACT that I answered incorrectly with H. It illustrates an important rule regarding commas in a series that I'm still mixing up. The gray highlighted portion can be changed with any of the answers below:

Salad Greens and herbs, such as arugula, Swiss chard, black kale, rapini, sage, and oregano, shared one large plot, given their similar moisture requirements.

F. NO CHANGE

G. herbs – such as arugula, Swiss chard, black kale, rapini, sage, and oregano

H. herbs, such as arugula, Swiss chard, black kale, rapini, sage, and oregano

J. herbs; such as arugula, Swiss chard, black kale, rapini, sage, and oregano

The ACT always requires the Oxford comma. However, I can't find examples of what to do with the last item in a series if the sentence continues after the last item. In this example, only F sets off the last item (oregano) with a comma from the rest of the sentence. Is this comma always necessary after the last item in a series if the sentence continues or is that not always the case but just happens to be so in this example?

Answer 1

The sentence includes parenthetical nonessential information. You can parse it like this:

Salad Greens and herbs (xxx) shared one large plot . . .

To maintain this construction, you need to use a pair of some some kind of punctuation mark: the parentheses I used in my example (which isn't one of the available answers), commas, or dashes.

None of the proposed replacement options offer a phrase that concludes with a second punctuation mark.

Therefore, the only option that's available is the original—which results in a pair of commas:

Salad Greens and herbs, xxx, shared one large plot . . .

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Note that if there is no parenthetical nonessential information, that a closing punctuation mark (as the second in a pair) is not required.

For instance:

(Essential) "I ate cheese, crackers, and olives for a snack before dinner."
(Parenthetical nonessential): "I ate a snack, which included cheese, crackers, and olives, before dinner."