Step 1: Understand statements
- The statements describe crowded buses and competition with motor cars in the streets.
- These indicate travel challenges, but do not explicitly state traffic jams.
Step 2: Analyze conclusions
- Conclusion I: "Traffic jam is inevitable in big cities" is a generalization not directly supported by the statements.
- Conclusion II: "Traveling is very difficult for city people" logically follows due to crowding and competition described.
Thus, only conclusion II logically follows.