How did American business in the 1920s attempt to solve the problem of developing enormous universal markets for its mass-produced goods?

AAmerican business developed a large range of product variations.

BAmerican business nurtured the birth and development of consumer advertising.

CAmerican business engaged in fierce price-competition wars.

DAmerican business introduced direct selling through catalogues and door-to-door solicitations.

EAmerican business offered government-backed guarantees on product performance.