In the context provided, the word "alternative" refers to a different option or choice that can be taken instead of another. In this case, it implies that online learning is a different method of education compared to traditional in-person schooling. The best synonym among the provided options would be "chance," as it suggests an opportunity or option.
However, note that none of the options directly correspond to "alternative" as primarily used in this context. If "option" had been one of the choices, that would have been the best fit.
Considering the given options, I would say "chance" is the closest, although it's not a perfect match.