One of the main teachings of Laozi was (4 points) a
to let nature take its course
b
to respect one's parents
0
C
to honor dead relatives from the past
od
to serve society by joining the military

offline recommendation systems option b

because recommendation systems produce a list of two ways

1. through collaborative filtering

or

2. through content-based filtering

explanation:

the addition to geographic boundaries that might have  kept the people of the huang river civilization from traveling to far distance region is that they had learned about the other river valley civilizations but feared contact would bring invasion.

hope this .

plz give me brainliest!

the china one is last

explanation: