Final answer:
By the late 1980s, high-fructose corn syrup had significantly replaced cane sugar in the US market due to supportive farm policies making corn a cheaper alternative, despite health concerns and controversy.
Step-by-step explanation:
By the late 1980s, high-fructose corn syrup (HFCS) had become a predominant sweetener in the US market, largely replacing cane sugar. This shift was driven primarily by US farm policies that supported corn production, making it an abundant and cheaper alternative to granulated sugar. As a result of these factors, as well as the controversies surrounding HFCS and its alleged impact on health and obesity, certain sections of the market began to see a re-emergence of products made with natural sugar.
Nevertheless, corn syrup and other corn-derived sweeteners continued to represent a significant proportion of the sweetener market. Additionally, the attempt by manufacturers to rebrand HFCS as 'corn sugar' was rejected by the FDA, indicating the strong association of HFCS with negative health perceptions.