Which of the following best defines emancipation? the purchase of an enslaved person the end of the practice of slavery the freeing of all enslaved people the practice of educating enslaved people

The emancipation can be best defined as the freeing of all enslaved people. This is because abolition would be the end of the practice of slavery. Therefore, when referring to emancipation, we're talking about letting people free, and not necessarily abolishing slavery (even if both emancipation and abolition happened at the same time). In the United States, the Emancipation Proclamation was made by Abraham Lincoln in 1863.

to act quickly in times of danger to the united states

because you have to act quickly if you want to live/survive.