The phrase "a shrewd negotiator" is an interrupting phrase, a phrase that has no bearing on the construction of the sentence but provides additional information. All interrupting phrases must be set apart by commas; therefore, the correct answer choice is "The executive, a shrewd negotiator, always."

The phrase "anxious about their grades" is an interrupting phrase, or one that provides extra information, but is not crucial to the structure of the sentence. All interrupting phrases need to be set apart from the rest of the sentence by commas. The only answer choice that does this is "The students, anxious about their grades, were."

The list that forms the subject of the sentence, "Angles, Jutes, and Saxons," appropriately separates its items with commas. The comma between "Saxons" and "were" splits the subject of the sentence from the verb, and should be removed. This makes "Angles, Jutes, and Saxons were" the correct answer choice.

The list of names that forms the subject of the sentence is written incorrectly. All lists need to have commas separating their parts from each other for purposes of clarity. The correct answer choice is "Jane, Sally, and Suzy all went to the zoo together."

The list of names that make up the subjects of the sentence all need to be appropriately punctuated. Any such list needs have all the elements set apart from each other; therefore, "Tom, Dick, and Harry have all seen" is the correct answer.

The list that functions as the subject of the sentence needs to have commas separating its elements, distinguishing the different parts. The only answer choice that does this is "Politicians, organizers, and reformers all came together," making it the correct answer choice.

A list like the one in the underlined portion of the sentence must always be appropriately separated out, especially when the elements of the list are two words, like "foreign policy." The only answer choice that clearly delineates the three component parts of the list is "economics, foreign policy, and health care."

Any list like the one used as the subject of the sentence needs to have its elements separated by commas to distinguish the separate parts. The only answer choice that appropriately does this is "The athletes, musicians, and actors," with every other answer choice being grammatically incorrect.

A list like the one in the underlined portion of the sentence always needs to be separated by commas to clearly distinguish between the different elements in the list. The only answer choice that correctly does this is "Rowing, lacrosse, and tennis are," making it the correct answer choice.

The three-part list that is the subject of this sentence does not employ appropriate demarcation between its separate parts. Lists like the one in the sentence need to be separated out by commas to show their individual parts. "Dogs, cats, and small animals have always been" is the only answer choice that appropriately deploys commas in the list.