Between 1950 and 2000, the number of independent states

remained the same
increased slightly
decreased slightly
increased significantly
decreased significantly

increased significantly

Explanation:

Between the peroid of the 1950 and the 2000 many of the states have gained and increased on numbers very significantly like the Albania, the Austria, Bulgaria, Libya, etc.

Your answer is d. silli hope this ! : ) i left an explanation down below if you need it: a sill forms when hot magma squeezes between layers of rock to form a hardened sheet of rock. a sill is basically a tabular sheet intrusion between old layers of sedimentary rock, volcanic beds, or in the direction of foliation inherent in metamorphic rock. the word sill means a concordant intrusive sheet.