Match the following products with the suitable manufacturing process

Product		Manufacturing Process
P	Toothpaste tube	1	Threaded bolts
Q	Metallic pipes	2	Blow moulding
R	Plastic bottles	3	Rolling
S	Threaded bolts	4	Impact extrusion

The correct option/answer is P-4, Q-1, R-2, S-3.

Here is the detailed step-by-step matching of each product to its most suitable manufacturing process:

1. Toothpaste tube (P → 4)
Toothpaste tubes (especially metal collapsible ones) are thin-walled, hollow tubular sections with a closed bottom. They are manufactured using impact extrusion (specifically backward impact extrusion). In this process, a punch strikes a metal slug placed in a die cavity at high speed, forcing the material to flow upward through the clearance between the punch and the die to form the thin-walled tube shape in a single stroke.

2. Metallic pipes (Q → 1)
Although the option list contains a slight typographical repetition where process 1 is listed as "Threaded bolts", in manufacturing terminology (and the original standard problem), process 1 represents centrifugal casting. Centrifugal casting uses a rotating mold to distribute molten metal outwards toward the mold walls by centrifugal force, making it the ideal process for manufacturing hollow cylindrical structures such as metallic pipes without using a core.

3. Plastic bottles (R → 2)
Hollow plastic items such as beverage bottles, shampoo bottles, and containers are manufactured using blow moulding. In this process, a heated plastic tube (called a parison) is placed inside a split mold cavity and air is blown into it, expanding the plastic to conform to the inner shape of the mold.

4. Threaded bolts (S → 3)
Threaded bolts are typically manufactured using the rolling process (specifically thread rolling). In thread rolling, a cylindrical blank is rolled between flat or circular dies that have the thread profile. The material undergoes plastic deformation to form the threads. This method is highly preferred over thread cutting because it increases the tensile strength of the threads and provides a better surface finish.

Therefore, the complete matching sequence is:
P → 4 (Toothpaste tube → Impact extrusion)
Q → 1 (Metallic pipes → Centrifugal casting / Process 1)
R → 2 (Plastic bottles → Blow moulding)
S → 3 (Threaded bolts → Rolling)