If "train" is called "bus", "bus" is called "tractor", "tractor" is called "car", "car" is called "scooter", "scooter" is called "bicycle" and "bicycle" is called "moped", then which of these vehicles is used to plough a field (according to the new naming system)?

Introduction / Context:
This question checks whether you can keep track of relabelled objects. The physical objects remain the same, but their names are changed in a chain. You must figure out which new name refers to the vehicle that is actually used for ploughing a field.

Given Data / Assumptions:
train → called bus.
bus → called tractor.
tractor → called car.
car → called scooter.
scooter → called bicycle.
bicycle → called moped.
We know from real life that a tractor is the vehicle commonly used to plough fields.

Concept / Approach:
The core idea is to separate the real object from the new label. We begin with the real object "tractor" (the field ploughing vehicle) and look up what new word is being used for it in this naming system. That is all we need; the other name changes are distractors.

Step-by-Step Solution:
Step 1: Identify the real world answer: the vehicle used to plough a field is a tractor. Step 2: According to the renaming chain, "tractor" is called "car". That means whenever we speak of a real tractor in this code language, we now use the word "car". Step 3: Therefore, if the question asks which of the options is used to plough a field under the new naming system, we must choose "car".

Verification / Alternative check:
Note that "bus" is the new name for a real train, not for a tractor. "train" is the new name for nothing that ploughs fields. "tractor" in this code is the name for a real bus, not for the farm vehicle, so it cannot be the right choice in the coded context. Only "car" is tied directly to the real tractor by the given mapping.

Why Other Options Are Wrong:
Train, bus and tractor as options reflect either different objects or new names for other objects in the chain. None of them correspond to the real tractor under the new naming rule. Hence they cannot represent the field ploughing vehicle when viewed through the code.

Common Pitfalls:
Many students are tempted to choose "tractor" because they focus only on the real world meaning and ignore the renaming entirely. Others get lost in the chain of mappings. Always begin with the real object and replace its name exactly once using the given rule to find the coded answer.

Final Answer:
In the new naming system, the vehicle used to plough a field is called a Car.