Answer: False.
Explanation: The statement that we have here is:
México es el único país que celebra la semana santa.
and a rough translation of this is:
"Mexico is the only country where is celebrated the Holy Week"
This is false, the Holy Week is a Christian "celebration" that comes before Easter, this week is celebrated (maybe in different ways) in a lot of countries and cultures, so the statement is false, there are other countries that also celebrate the Holy Week, an easy example can be most (if not all ) of the other Hispanic countries.