Mandarin chinese is not spoken widely outside of china, yet it is spoken by more people than any other language. what makes this possible?

It is possible because the population of China is very large.

Immigration? Because many Chinese left China due to civil wars and riots? When they marry or live with locals, they might spread the knowledge of the language

Answer cumulus clouds;

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.