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The right answer is J. The adjectives moist, mesic, and dry constitute a list of three different things that sand prairies can be. Therefore, commas are necessary after moist and mesic. (Although the comma before the conjunction that separates the final two items in a list is optional when the conjunction is and, it is mandatory when the conjunction is or!) The word dry ends one independent clause, which then needs to be joined to the subsequent one via a comma + conjunction, and so a comma is also necessary after dry.
The right answer is NOT F because it omits the necessary commas after moist, mesic, and dry.
The right answer is NOT G because it omits the necessary comma after moist and incorrectly replaces the necessary comma after dry with a semicolon.
The right answer is NOT H because it omits the necessary comma after mesic and incorrectly replaces the necessary comma after moist with a colon.