A lexical allies sign refers to a term that is part of the same category or relates closely to another term in meaning or concept. In the context of transportation, all the options you provided - Car, Bike, Train, and Plane - fall into that category. However, if you are looking for a specific type of lexical ally among them, it would depend on the classification you're considering (land transport vs. air transport).
For instance:
- Car, Bike, and Train are all forms of ground transportation, making them lexical allies in that context.
- Plane stands alone as it refers to air transportation.
If you need a specific example or further details, please clarify!