Standards act as barriers to trade because they force imported goods to meet certain criteria. (Option D)
How is that so?
Standards are documented agreements containing technical specifications or other precise criteria to be used consistently as rules, guidelines, or definitions of characteristics to ensure that materials, products, processes, and services are fit for their purpose.
In simpler terms, they are agreed-upon ways of doing things that help ensure quality, safety, and consistency. There are organizations that ensures that these standards are met and followed.