I like the combination of a blue jean and white t-shirt
They're just perfect for some casual wears and outings. 
Yes also we can wear color shirts. But we should not wear black in summer.
sure, black do absorbed a lot of heat. Jean are made with variety of materials.
Yes But what type of material is jean produced
Most jeans are produced with 98% denims and 2% cottons. but both belong to fabric. 
Oh I see. So I think they are health friendly. What do you think about it?
Exactly. Denim are noted for strength and comfort. They are fashionable also. 
Yes They are fashionable too. That is what we want. So we can choose a jean and a t-shirt as a casual wear.
Sure, although not for all occasions. Jeans and T-shirt are great wears.