The sentences given below, when properly sequenced, form a coherent paragraph.
Each sentence is labelled with a number. Decide on the most logical order and enter the sequence of numbers in the space provided. Only numbers are to be entered in the space provided for the answer, and no letters, characters, or spaces should be entered. For example, a response such as 3412 is valid, and responses such as 3412. or 3 41 2 are invalid.

1. Once they reach a high altitude, they manage to travel all over the world.
2. An expert from the team explained that the bacteria usually lived on the surface of vegetation, such as leaves.
3. The wind carries them off the surface and into the atmosphere.
4. A group of researchers were surprised to find that clouds had carried drug resistant bacteria over a long distance.