The law of conservation of mass states that mass in an isolated system is neither created nor destroyed by chemical reactions or physical transformations. According to the law of conservation of mass, the mass of the products in a chemical reaction must equal the mass of the reactants. The law of conservation of mass is useful for a number of calculations and can be used to solve for unknown masses, such the amount of gas consumed or produced during a reaction.
Your answer is D. Cretaceous. The Cretaceous Period extends from circa 145 million years ago to 66 million years ago. During the Cretaceous, the late Paleozoic-early Mesozoic super continent of Pangaea completed its breakup into present day continents, although their positions were substantially different at the time.
Many scholars believe that the collapse of the Indus valley civilization was caused by climate change...By 1800 BCE, the Indus valley civilization climate grew cooler and drier , and a tectonic event many have diverted to disrupted river systems
