The phrase "Much like his father" is an introductory phrase, one that conditions the meaning of the sentence but remains apart from its structure. Any introductory phrase must be set apart from the main part of the sentence by a comma. The only answer choice that appropriately uses such a comma is "Much like his father, he had no use for opera or classical music in general."

The phrase "In his public corruption trial" is an introductory phrase, one that conditions the meaning of the sentence, but remains apart from its structure. All introductory phrases must be set apart from the rest of the sentence by a comma. The only answer choice that appropriately does this is "In his public corruption trial, the ex-governor swore he had no knowlege of what his chief of staff was doing."

"Working on the book his whole life" is an introductory phrase, one that conditions the action of the sentence, but is set apart from its main structure. All introductory phrases need to be set off by a comma from the rest of the sentence. "Working on the book his whole life, the author's novel" is the only answer choice to properly use a comma in this manner.

The phrase "After the details were worked out" is an introductory phrase, one that conditions the meaning of the sentence, but remains apart from its basic structure. Any introductory phrase needs to be set apart from the rest of the sentence by a comma. "After the details were worked out, the two sides still took" is the only answer choice that appropriately deploys the comma.

"In the Middle Ages" is an introductory phrase, a phrase that conditions the meaning of the sentence, but remains outside its main structure. Any introductory phrase must be set apart by a comma from the rest of the sentence. "In the Middle Ages, few peasants were ever able" is the only answer choice to appropriately use such a comma.

"Unlike his brothers" is an introductory phrase, one that conditions the meaning of the sentence, but remains outside its main structure. Any introductory phrase must be set apart from the rest of the sentence by a comma. "Unlike his brothers, the little boy hated" is the only answer choice that correctly uses a comma.

"Under the new treaty" is an introductory phrase, one that condistions the action of the sentence, but remains outside of the sentence's main structure. An introductory phrase must always be set off by a comma. The only answer choice that correctly sets off the phrase is "Under the new treaty, neither side could put defensive works along their border."

"In the previous case" is an introductory phrase, one that conditions the meaning of the sentence, but remains separate from the main body of the sentence. Any interrupting phrase must be set off from the main portion of the sentence by a comma. The only answer choice that correctly sets off the phrase is "In the previous case, the exact same weapon was used."

"Under the teacher's guidance" is an introductory phrase, one that conditions the action of the sentence, but is apart from its main structure. Any introductory phrase needs to be set apart fom the main body of the sentence by a comma. The only answer choice that correctly uses a comma to separate the phrase is "Under the teacher's guidance, the students' reading ability improved."

"Unlike his family" is an introductory phrase, one that conditions the action of the sentence, but remains apart from its main body. Any introductory phrase must be set apart from the rest of the sentence by a comma. The only answer choice that correctly uses the comma is "Unlike his family, the man became deeply religious as he got older."