a massive extinction of about 50% of marine animals occurred at the end of the mesozoic era. what most likely caused this extinction?

We the people of the united states, in order to form a more perfect union, establish justice, insure domestic tranquility, provide for the common defence, promote the general welfare, and secure the blessings of liberty to ourselves and our posterity, do ordain and establish this constitution for the united states of america. according to the preamble which action represents an appropriate role for government

What undergraduate degree can a student earn at a four-year college (not specific to a field of study)?

How do we determine if they are made with matter