$30 \cdot 9$ There are 18 teams participating in the opening ceremony of the competition. When entering, the 1st team has 27 people, the 2nd team has 26 people, ..., the 18th team has 10 people. If they all enter in a single-file line, and all representatives of the 18 teams are numbered $1,2, \cdots, 333$ in the order of their entry. Then the number of teams whose last representative is assigned an odd number is
(A) 8.
(B) 9.
(C) 10.
(D) 11.
（2nd "Five Sheep Cup" Junior High School Mathematics Competition, 1990）
[Solution] The last representative of the 1st team is numbered 27, the last representative of the 2nd team is numbered $27+26=53$, the last representative of the 3rd team is numbered $27+26+25=78$, and the last representative of the 4th team is numbered $27+26+25+24=102$,

Thus, the numbers of the representatives follow a pattern of odd-odd-even-even-odd-odd …… cyclically. Since there are 18 teams in total, 10 teams have their last representative numbered as an odd number. Therefore, the answer is $(C)$.