Question: I want to transmit data from multiple sensors to an Arduino and distance would be approximately 120 meters.

What protocol or configuration should I use?

Actually I am trying to read values from 5 temperature sensors located in 5 different spots of warehouse. I want to read them and trigger some relay based on the values.

I thought about I2C but I have read somewhere that its not built for long distances. Also thought about RS-485, but I don't know if that supports bus (connect all sensors to same line).

Which solution do you suggest?

Answer: 
While thinking about RS-485, did you read about it? It is a bus. It is designed for long distances.
I2C is not built for long distances (max. some meters) But you can make it via RS485, But you will need to add termination resistors to each end.