2. (10 points) The distance from Xiaoming's home to school takes 30 minutes by subway, and 50 minutes by bus. One day, Xiaoming had to take the subway first and then switch to the bus, and it took him 40 minutes to reach the school, with the transfer process taking 6 minutes. How many minutes did Xiaoming spend on the bus that day?
A. 6
B. 8
C. 10
D. 12
【Analysis】The total time used is 40, minus the transfer time of 6 minutes. $40-6=34$ minutes. The subway takes 30 minutes, the bus takes 50 minutes, and the actual time is 34 minutes. According to the time difference, the method of proportional shares can be used.

【Solution】The travel time is $40-6=34$ minutes. Assuming it is all by subway, which takes 30 minutes, the time difference is $34-30=4$ minutes, which needs to be adjusted to delay the bus by 4 minutes. The time ratio of subway to bus is 3:5. Let the subway time be 3 parts, and the bus time be 5 parts.
$$
4 \div(5-3)=2 \text{, }
$$

The bus time is $5 \times 2=10$ minutes.
Therefore, the answer is: $C$.