A．Because they were searching for better land.B．Because the population was increasing.C．Because western parts were more prosperous than eastern parts in these two countries.D．Because eastern parts in these two countries had been occupied by the Spanish.
A．Because they were searching for better land.
B．Because the population was increasing.
C．Because western parts were more prosperous than eastern parts in these two countries.
D．Because eastern parts in these two countries had been occupied by the Spanish.