This comes form complicated nature of the word nosić/nieść = carry , among other meanings In this meaning niosę= i am carrying noszę = I carry
You use noszę = I wear, but not I am wearing ,
So, that means that the question "Nosisz brazowe spodnie?" is asking if the person wears brown pants in a general sense, not if the person is currently wearing brown pants? (I'm just trying to wrap my head around whatever this nosic/niesc distinction is - I've seen aspect in other Slavic languages but this seems different.)
Most of the Engish speaking world says pants rather than trousers. Pants as underwear is a regionalism.