9. (1983 American High School Mathematics Examination) Three balls marked $1,2,3$ are placed in a jar. A ball is drawn from the jar, its number is recorded, and then it is returned to the jar. This process is repeated three times, with each ball having an equal chance of being drawn each time. If the sum of the recorded numbers is 6, then the probability that the ball marked 2 was drawn all three times is ( ).
A. $\frac{1}{27}$
B. $\frac{1}{8}$
C. $\frac{1}{7}$
D. $\frac{1}{6}$
E. $\frac{1}{3}$
9. C. Reason: Because there are a total of 7 scenarios where the sum of the digits of the balls drawn is 6, and they are equally likely.

Using the following ordered triples to represent them:
$$
(1,2,3),(1,3,2),(2,1,3),(2,3,1),(3,1,2),(3,2,1) \text { and }(2,2,2) \text {, }
$$

Therefore, the probability that the ball marked 2 is drawn all three times is $\frac{1}{7}$.