Which of these human activities is a serious threat to marine ecosystems? a) fishing in estuaries. b) dumping wastes in landfills. c) sinking chemical wastes in the ocean. d) burning wastes rather than dumping them in landfills.

specific gravity is the density of a substance divided by the density of water. since (at standard temperature and pressure) water has a density of 1 gram/cm3, and since all of the units cancel, specific gravity is usually very close to the same value as density

so "c" is the answer

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