To understand which group a **towed agricultural machine** belongs to, it is important to know the definitions of the different types of special vehicles.

- **Towed vehicles**: These are vehicles that do not have their own engine and need to be pulled by another vehicle. Within this category, we find the **agricultural trailer**, which is specifically used for work in the field and must be pulled by a tractor or another special vehicle.

- **Towed machine**: Similar to the agricultural trailer, this machine also needs to be pulled by another special vehicle. It is used for work in the field, on construction sites, or in other services.

- **Tractor**: It is a vehicle with a powerful engine, mainly used to pull or transport materials in the field or in construction. Agricultural tractors are the ones that commonly pull agricultural trailers.

Since a **towed agricultural machine** is a type of vehicle used in the field and needs to be pulled, it belongs to the group of **special towed agricultural vehicles**. This differentiates it from self-propelled vehicles, which have their own engine and do not need to be pulled.