Answer:
Appreciated.
Step-by-step explanation:
Currency pegging occurs when a country attaches, or pegs, its exchange rate to another currency, this pegging stabilizes the exchange rate between countries and what happens to one, happens to the other. Most countries are pegged to the US dollar.
In this example the currency of country X is pegged to that of country Y, during the last week, Country Y's currency appreciated against the dollar, thus, since they are pegged (or in other words, attached), what happens to one will happen to the other.
Thus, the currency of country X appreciated against the dollar during the last week too.