Final answer:
The container management system uses methods such as tracking changes in file timestamps or comparing previous and current versions of the container image to determine if only one layer has been changed and then transport only that specific layer.
Step-by-step explanation:
The container management system knows that only one layer has been changed through various methods such as tracking changes in file timestamps or comparing the previous and current versions of the container image. By comparing these attributes, the system can identify if only one layer has been modified and then transport only that specific layer instead of the entire container image.