The phrase "said to be slimming" is an interrupting phrase, a phrase that provides extra information to a sentence, but is not a crucial part of its structure. Any interrupting phrase must be set off from the rest of the sentence by commas. Therefore, the correct answer choice is "Black clothing, said to be slimming, actually depends on the wearer’s shape for its slimming qualities."

The phrase "which broke new ground in the medium" is an interrupting phrase, a phrase that provides information but is not crucial to the structure of the sentence. All interrupting phrases must be set apart from the rest of the sentence by commas. The only answer choice that appropriately does this is "The advertisement, which broke new ground in the medium, remained."

The phrase "a familiar presence on local radio" is an interrupting phrase, one that provides extra information to the sentence but is not part of the sentence's necessary structure. All interrupting phrases must be set apart from the rest of the sentence by commas. The only answer choice that correctly sets off the interrupting phrase is "The sportscaster, a familiar presence on local radio, announced his retirement earlier this month, at the age of eighty-seven."

The phrase "Moving away from his hometown" is an introductory phrase, one that conditions the main action of the sentence while remaining separate from the sentence's main body. All introductory phrases must be set apart from the rest of the sentence by a comma. "Moving away from his hometowm, the college student wanted" is the only answer choice that appropriately does this.

The phrase "making up for lost time" is an interrupting phrase, one that adds extra information to the sentence, but remains apart from its structure. All interrupting phrases must be set apart from the sentence by commas. "The driver, making up for lost time, started driving much faster" is the only answer choice that correctly does this.

The phrase "a long-time veteran of the police department" is an interrupting phrase, one that provides extra meaning to the sentence while remaining apart from its structure. All interrupting phrases need to be set apart from the rest of the sentence by commas. "The commanding officer, a long-time veteran of the police department, had" is the only answer choice to appropriately separate out the phrase.

The phrase "changing his management style" is an interrupting phrase, one that provides extra information to the sentence, but sits outside the sentence's main structure. All interrupting phrases must be set apart by commas from the rest of the sentence. "The new executive, changing his management style, began" is the only answer choice that properly does this.

The phrase "having never failed to get a date for one of her clients" is an extremely long interrupting phrase, a phrase that adds information to a sentence but remains outside the main structure of the sentence. All interrupting phrases must be set apart from the rest of the sentence by commas. The only answer choice that appropriately does this is "The matchmaker, having never failed to get a date for one of her clients, worked desperately before her deadline from her new client."

The phrase "already a large local story" is an interrupting phrase, one that provides extra information to the sentence but remains apart from its main structure. Every interrupting phrase needs to be set apart from the rest of the sentence by commas. The only answer choice that properly does this is "The event, already a large local story, was further fueled by national news coverage."

The phrase "an aging war veteran" is an interrupting phrase, one that provides extra information to a sentence, while sitting outside the sentence's main structure. All interrupting phrases must be set apart from the rest of the sentence by commas. "The grandfather, an aging war veteran, held court" is the only answer choice that appropriately uses commas around the phrase.