Which word or words and punctuation best corrects any errors in the sentence?

she packed six shirts, three pairs of jeans, pajamas, and a cosmetics bag but the key to the suitcase was left behind on her desk.

a.
there is no error in this sentence.

b.
packed:

c.
bag, but

d.
bag; but

The word and the punctuation that best corrects any errors in the sentence is option C. bag, but. A comma should be placed after the word bag because another clause is introduced by the coordinating conjunction "but". So the correct sentence should be, "She packed six shirts, three pairs of jeans, pajamas, and a cosmetics bag, but the key to the suitcase was left behind on her desk."