Answer:
B. A, B, C
Explanation:
Coordinate headings assume using the same type of marking for starting a new chapter. Those can be Arabic or Roman numerals, uppercase and lowercase numerals, cardinal and ordinal numbers, but the author should always use just one of them, not a mixture.
Only in the answer B we find such a marking with using uppercase letters A, B and C.
On the other three answers we have a mixture of Arabic and Roman numerals, uppercase and lowercase letters.
