The correct answer is option 4, Petrol. Petrol is not currently covered under the Goods and Services Tax (GST) regime in India. The GST is a comprehensive tax levied on the supply of goods and services across the country, with the aim of creating a unified market. However, certain items have been exempted from the purview of GST, and petrol is one of them. This means that the existing indirect taxes, such as excise duty and value added tax (VAT), continue to be applicable on petrol.

Options 1, 2, and 3, namely cosmetics, medical grade oxygen, and jewellery, are covered under GST. This means that these items are subject to the tax and their sale and purchase are regulated under the GST system.

It is important to note that the tax structure and exemptions under GST are subject to change as per government policies and amendments. Therefore, it is essential to stay updated with the latest notifications and changes in the GST regime.