According to the preamble, why was the constitution written? to provide power to the states to give power to the federal government to provide a common defense

From those choices, the correct answer is:  to provide a common defense.

"A common defense" is just one of several purposes stated in the Preamble.  The Preamble to the US Constitution says:  "We the People of the United States, in Order to form a more perfect Union, establish Justice, insure domestic Tranquility, provide for the common defense, 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."

Incidentally, the term "preamble" stems from the Latin compound word "praeambulus" (prae + ambulus), meaning "walking before" or "going before."  So a "preamble" is an introductory statement to something, going before the main content of the document itself.

yes

explanation:

why

answer: the time zones used to be whatever the local authority wanted them to be. one town might have 6am whenever the sun came up and another town had 6am 10 minutes later.  

the trains had a hard time when their orders said to be at a certain point at 6am.  

6am, but who's 6am.  

the railroads got together and set the time zones more or less along the longitude lines across the country.

explanation: