Dear Kalaiyarasan, its understandable with the summer heat knee length trousers might seem comfortable but comfort is the wrong term to be seeking for your examination. Your goal is to appear for your exam uninterrupted, and unncessary questions asked. If the rules state, you shall attend the exam in trousers then full length trousers is the word. There can be no tweaking to it. You dont want unncessary speculation and so please avoid any trousers that have lesser pockets. Clothes need to be as simple and as light they can be without any zips, pockets, big buttons and embroidery in elaborated sense. There were instances where in candidates have been turned away from the examination hall when they did not comply with the dress code. "I thought it is allowed" cannot save you there. So we would suggest you to stick to the dress code. Please have a look at this article for better understanding: https://medicine.careers360.com/articles/neet-dress-code