Rana should buy shirts made from cotton. This is because cotton is a good absorber of water. It can soak the sweat coming out of our body and expose it to the environment. Thus, it helps in evaporating the liquid (sweat), thereby cooling our body.
Synthetic fibres on the other hand are water repellent. They do not absorb water (sweat) and hence the sweaty clothes will stick to our body, making us feel uncomfortable.