4. 10 people sit around a round table, each choosing a number and telling it to their two neighbors, then each person reports the average of the two numbers they heard. Figure 1 shows the numbers everyone reported. Then the person who reported the number 6, the number he originally chose is ( ).
(A) 1
(B) 3
(C) 2
(D) 6
4.A.

Let the number originally chosen by the person who reported the number 6 be $x$. According to the problem, the numbers originally chosen by the people who reported the numbers $4, 2, 10, 8$ are $10-x, x-4, 6-x, x+12$ respectively. Therefore, we have
$$
x+x+12=2 \times 7 \text {. }
$$

Solving for $x$ gives $x=1$.