Answer
“While that link gave the English a stake in slavery, it also gave the antislavery forces an opportunity.”
Explanation
The antislavery movement were the ones who ended slavery; they were the ones who convince the general public that slavery was a despicable practice which, in time, lead to the abolition of it.
Let's analyze each quotation:
“The English public . . . knew little about the lives of the enslaved Africans whose labor sweetened their meals.” Even after the general public knew the horrors of slavery, a lot them still support it, so we can rule out this one.
“Every Englishman who . . . built the barrels to hold slave-harvested sugar made his money from the slave trade.” This one is telling us nothing about ending slavery; it is just telling us that some people make money with it.
“The English were getting richer because Africans were being turned into property.” Same argument as before.
“While that link gave the English a stake in slavery, it also gave the antislavery forces an opportunity.” This quotation is telling us that while some people supported slavery, there were also people willing to fight against it. That fight led to the abolition of slavery, and that fight wasn't been possible without the horrors of sugar trading.