Which amendment to the constitution ended slavery in the united states?

It was the 13th Amendment.  It ended slavery when it was approved by Congress.  Prior to this Lincoln also establish the Emancipation Proclamation. This Amendment totally abolished slavery.  With this all men were now considered equal.  Though there was still work to be done this led to the end of slavery in America.

offline recommendation systems option b

because recommendation systems produce a list of two ways

1. through collaborative filtering

or

2. through content-based filtering