**Needle : Thread :: Bike : Petrol**

To understand the analogy between "Needle : Thread" and "Bike : Petrol," let's break down the relationship between needle and thread first.

**Needle : Thread**

A needle and thread are objects that are commonly used together in sewing. The needle is the tool that is used to pass the thread through fabric, creating stitches. Without the thread, the needle would be ineffective in sewing.

The thread, on the other hand, is the material that is passed through the needle and used to create the stitches. It is the essential component that enables the needle to fulfill its purpose.

Therefore, in the analogy, the relationship between needle and thread is that of a tool and its essential component, where the tool (needle) requires the component (thread) to function effectively.

**Bike : Petrol**

Now, let's analyze the relationship between a bike and petrol to determine the correct answer.

A bike is a mode of transportation that typically operates with the help of an engine. Similarly, a car runs on petrol or gas, enabling it to move forward. Petrol serves as the fuel that powers the bike's engine, allowing it to function and propel forward.

Just as the needle requires thread to fulfill its purpose, the bike requires petrol to operate effectively. Without petrol, the bike would be unable to function and would be rendered useless as a means of transportation.

Therefore, the correct answer is option A) Petrol, as it is the essential component that allows the bike to fulfill its purpose, similar to how thread enables the needle to fulfill its purpose in sewing.

To summarize:
- Needle requires thread to sew effectively.
- Bike requires petrol to operate effectively.
- Therefore, the analogy between "Needle : Thread" and "Bike : Petrol" is that of a tool and its essential component.