In which of the following are hydrogels used? 1. Controlled drug delivery in patients 2. Mobile air-conditioning systems 3. Preparation of industrial lubricants Select the correct answer using the code given below:

1, 2 and 3

Statement 1 is correct because hydrogels can absorb and retain water and are used in controlled drug-delivery systems. Statement 2 is correct because hydrogel-based materials can absorb moisture and support evaporative or desiccant-based cooling in air-conditioning applications. Statement 3 is also correct because hydrogel and water-rich polymer systems can be formulated for lubrication in industrial and specialized applications. Therefore, all three statements are correct. Options A, B and C are incorrect because each excludes at least one genuine application of hydrogels.