Mammals first appeared during the Mesozoic Era. The correct option among all the options that are given in the question is option "c". The Mesozoic Era is considered to have lasted for about 180 million years. The Mesozoic Era is divided into three parts and they are the Triassic, the Jurassic and the Cretaceous. The mammals are considered to have evolved during the Triassic period.
The system of checks and balances ensures that the federal government does not abuse the necessary and proper clause through the use of the judicial branch.
The judicial branch (aka Supreme Court) has the ability to rule federal laws/acts constitutional or unconstitutional. In other words, if Congress tries to overstep their boundaries in terms of what actions they can take, the Supreme Court can rule their actions unconstitutional. This ruling would prevent Congress from acting, as all US citizens regardless of political power must follow the ruling of the Supreme Court.
The steps that countries must take to transition to a mixed-market economy are: they must establish a fair labor market, and they must open up trade to other countries.
A mixed economy is an economic system which mixes elements of market economies with elements of planned economies. It's a mixture of public and private enterprise.
So, to have a country with a mixed-market economy, countries must establish fair labor market to have adequate conditions for the labor market. Moreover, they must open up trade to other international countries. That is to say, to have free trade which doesn't restrict exports or imports.
