Panama lies between North and South America. It has an area of 77,000 square kilometers with a population of 1 ,771,000. Its official language is Spanish. Its capital is the largest city. Panama City.
Columbus visited Panama in 1502 on his fourth voyage(航海). It became Spanish colony (殖民地)at the beginning of the sixteenth century. In 1862, when Central America rose against Spain, Panama joined Colombia, which had already declared its independence(独立). It didn't break away from Colombia until the year of 1903 to become an independent republic.
The Panama canal is the country's biggest economic asset(经济资源). Panama and the United States reached an agreement in 1997, which declared Panama would take over all the rights of the Panama Canal in 1999.
Panama was a Spanish colony ______.

A. from the 16th century to the 18th century
B. until 1903
C. for about 200 years
D. for 300 years and more