The correct answer is option 3: 3, 1, 2.

The wholesale price index (WPI) is a measure of the average change in the prices of goods and services at the wholesale level. It takes into account various items to calculate the index, and each item is assigned a weightage based on its importance.

In this case, the items are:

1. Primary articles: These include agricultural and food products, as well as non-food primary articles like minerals, crude oil, and natural gas.

2. Fuel, power, lights, and lubricants: This category covers items like coal, electricity, diesel, petrol, and other sources of energy.

3. Manufacturing products: This includes finished products from various industries, such as textiles, chemicals, machinery, and metals.

To determine the weightage of each item, the importance of the item in the economy is considered. Generally, manufacturing products have the highest weightage as they represent a significant portion of the economy.

Therefore, in descending order of weightage, the correct arrangement is option 3: 3, 1, 2. This means that manufacturing products have the highest weightage, followed by primary articles, and finally fuel, power, lights, and lubricants.