Answer:
A, 3137 + 3791.
Step-by-step explanation:
You can test each answer, by hand or with a calculator, keeping the differences between the options carefully in mind.
A. 3137 + 3791 = 6928
B. 3137 + 3792 = 6929
C. 3237 + 3791 = 7028
Of these, A gives you 6928.