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."

Introductory or interrupting phrases, i.e. phrases that are subordinate and add information to a sentence, but are not necessary to the grammatical completeness of the sentence, must be separated from the rest of the sentence by commas. The best way to correct the underlined portion of the sentence above is: "While I can empathize with the plight of your lizard, I find..."

Introductory or interrupting phrases, phrases that are subordinate and add information to a sentence, but are not necessary to the sentence being grammatically complete, must be separated from the rest of the sentence by commas. The best way to correct the underlined portion of the sentence above is: "Emmett, well known for his pugnacious nature, was"

Introductory or interrupting phrases, i.e. phrases that are subordinate and add information to a sentence, but are not necessary to the sentence being grammatically complete, must be separated from the rest of the sentence by commas. In the sentence above "When we are so inundated by rain it is" should read "When we are so inundated by rain, it is."

Introductory or interrupting phrases, i.e. phrases that are subordinate and add information to a sentence, but are not necessary to the sentence's grammatical completeness, must be separated from the rest of the sentence by commas. In the sentence above "Chicago, a town known for its vociferous populace:" should read "The town, known for its vociferous populace," in order to be correct.

Introductory or interrupting phrases -phrases that are subordinate and add information to a sentence, but are not necessary to the sentence being complete- must be separated from the rest of the sentence by commas. In the sentence above "When I am feeling depressed nothing can cheer me up like a nice pint of my favorite ice cream," should read "When I am feeling depressed, nothing can cheer me up like a nice pint of my favorite ice cream."

Introductory or interrupting phrases -phrases that are subordinate and add information to a sentence, but are not necessary to the sentence being complete- must be separated from the rest of the sentence by commas. In the sentence above "Thor the norse god of thunder is" should read "Thor, the norse god of thunder, is."

Introductory or interrupting phrases -phrases that are subordinate and add information to a sentence, but are not necessary to the sentence being complete- must be separated from the rest of the sentence by commas. In the sentence above "Whenever you feel excited please take a moment to take thorough stock of the situation before you act," should read "Whenever you feel excited, please take a moment to take thorough stock of the situation before you act."

Introductory or interrupting phrases -phrases that are subordinate and add information to a sentence, but are not necessary to the sentence's completeness- must be separated from the rest of the sentence by commas. In the sentence above "I appreciate your concern but" should read "I appreciate your concern, but."

Introductory or interrupting phrases -phrases that are subordinate and add information to a sentence but are not necessary to the sentence being complete- must be grammatically separated from the rest of the sentence by commas. In the sentence above "If I were you I would" should read "If I were you, I would."