What was a result of creating rail standardization?
Railways were able to transport meat without spoilage.
Trains provided cars with pull-down beds for overnight travel.
Trains from different rail lines could use each other’s tracks.
Rail companies began to create their own styles of rails and tracks.

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.

The answer would be  b. hope this !