Before revision:  Thus, one faces a tradeoff between exploring the available treatments  and exploiting the best treatment, i.e. administering it as often as possible, in order to maximize the cumulative welfare of all the assignments made.
After revision:  Thus, one faces a tradeoff between exploring the available treatments to learn about their merits and exploiting the best treatment, i.e. administering it as often as possible, in order to maximize the cumulative welfare of all the assignments made.