Answer:
Gladstone asked the shipping company to provide workers.
Explanation:
The authors explain in the provided passage the way things went after the final end of slavery. They state how plantations depended on cheap labor and enslavement before, but that slaves were replaced by Indian people who were workers.
That idea can fully be seen in the sentence part “Gladstone asked it [a shipping company] to provide a hundred workers [...] from India”. It sums up how Gladstone asked for workers, instead of for slaves, for it, which refers to the previously mentioned shipping company. The passage then explains how many workers came with each ship to work for Gladstone.
