Why are pollen grains useful when studying the climate history of a region? they may contain the remains of ancient organisms. they may have rings inside them that reflect variations in the local climate. they can be preserved within the fossils of organisms that carry them. they provide clues about the types of plants that grew in a region at a particular time.

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.