Answer:
Because extraterrestrial life may exist astronauts when they come home, have to go through a certain quarantine process. Completing this process will to make sure there isn't something called the "back contamination" which is a germ of sorts that can be the cause of diseases we aren't used too. Then because of incubation period the safety protocols were very strict. Since how astronauts don't have anything to do with planet exploration and machines like rovers do, black contamination is really a problem. Sterilization of samples brought back was also in question but because astronauts don't bring anything like that back they do not have to worry about it.
Explanation:
Remember to summarize something is too give the important details of that something. In this case you read the source and take the most important details of that source into a four to five sentence summary which you have then summarized.
Hope this helps.
The problems
'Something that is already set up' ->established
'Take a chance/uncertainty' ->risk
'plans of action' ->strategies
'To give or add something' -> contribute
'A promise or obligation' -> commitment
The answer is B. Three important dates in U.S. history are July 4, 1776, April 9, 1865, and September 11, 2001. Hoped I helped. :)
