A comma is not needed between independent and dependent clauses when the independent clause comes first: "The President initially vetoed the bill in order . . ."

The phrase "with the only exception being Fridays" is a dependent clause, and needs to be clearly distinguished from the main clause of the sentence. The best way to do this is by setting a comma between the two parts. The only answer choice that correctly places a comma in the sentence is "He typically worked late, with the only exception being Fridays."

The phrase "despite having none to conduct" is a dependent clause, a clause that cannot stand as a complete sentence on its own, but provides extra explanation to the body of the sentence. A dependent clause always needs to be set apart from the rest of the sentence by a comma. The only answer choice that does this is "The former bandleader still dreamed about conducting an ensemble despite having none to conduct."

The phrase "which stressed their underlings" is a dependent clause, or a clause that relies on the main body of the sentence for its full meaning. Any dependent clause must be set apart from the main body of the sentence by a comma. The answer choice that appropriately uses such a comma is "The managers decided to make a change for no particular reason, which stressed their underlings."

The phrase underlined at the end of the sentence is one whole and complete phrase. Thus, the use of a comma anywhere in the phrase is grammatically incorrect. "Speculation by scholars" is the correct answer choice.

Use a comma to separate the introductory phrase "In many thrilling mystery novels" from the independent clause that in this case makes up the rest of the sentence, "the good guy actually turns out to be the bad guy."

The phrase "always careful with his words" is an interrupting phrase, one that adds information to the sentence, but remains apart from its structure. All interrupting phrases must be set apart from the rest of the sentence by commas. "The coach, always careful with his words, intentionally avoided" is the only answer choice to appropriately use commas around the interrupting phrase.

The words "a long time activist" are an interrupting phrase, that is a phrase which interrupts the sentence and is not necessary for proper sentence construction, but does provide information. Such phrases must be set off by commas on either end, so "leader, a long time activist, urged" is the best choice among the answers.

The phrase "annoyed with her class" is what is known as an interrupting phrase. An interrupting phrase provides information, but is not necessary to the construction of the sentence. All interrupting phrases need to be set apart by commas, making "The teacher, annoyed with her class, got emotional" is the correct answer.

The phrase "reached through faulty logic" is an interrupting phrase, or one that gives crucial information to the meaning of the sentence, but is not necessary to the sentence's construction. All interrupting phrases must be set apart from the rest of the sentence by commas, making "The conclusion, reached through faulty logic, proved" the correct answer choice.