Answer:
D
Explanation:
I'm only guessing it's D because from my understanding it is the most correct to myself.
Reasoning:
From point A to B it is 5
And from point B to C it is 6
So using normal math it can not be answers A or B.
Nor do I see it being C because, where did the 7 come from?
In the End, the answer must be D!
p.s. please correct me if I am incorrect, this is just the answer from my understanding