Which of these sentence segments does not contain a capitalization error in china, the city of kwangchow (formerly canton) is situated in the southwest part of china

You didn't make it clear which parts of the sentence form which sentence segments, but I can tell you this:

CORRECT: In China, the city of
INCORRECT: kwangchow (formerly canton)
CORRECT: is situated in the
INCORRECT: southwest
CORRECT: part of China