Trevor is a magician who amazes his audience by seeming to make objects disappear into thin air. he is exploiting his audience's for example, by distracting them with hand movements as he slips objects down his sleeves.

He is exploiting his audience's "change blindness".

Change blindness refers to a perceptual phenomenon that happens when an adjustment in a visual improvement is presented and the eyewitness does not see it. For instance, observers frequently neglect to see real contrasts brought into a picture while it flashes now and again again. People's poor capacity to identify changes has been contended to reflect crucial confinements of human consideration. Change visual impairment has turned into a profoundly investigated theme and some have contended that it might have imperative down to earth suggestions in regions, for example, observer declaration and diversions while driving.

the answer is b, encourage free trade