Take another look at the original sentence:

Tajuana is a very conscientious student when she makes a B, she is so upset that she lies awake at night, staring at the ceiling and worrying about the effect this "bad" grade will have on her GPA.

You chose to fix it the correct way:

Tajuana is a very conscientious student. When she makes a B, she is so upset that she lies awake at night, staring at the ceiling and worrying about the effect this "bad" grade will have on her GPA.

Tajuana is a very conscientious student is a complete sentence. When she makes a B, she is so upset ... begins the second complete sentence. You are always correct when you use a period and a capital letter between the two illegally joined sentences that create a fused sentence.

Go to the next sentence.

HomeTermsExercises MOOCHandoutsPresentationsVideosRulesAboutShopFeedback