What is the estimated population of ancient Copan? Of ancient Tikal?

18,000 to 25,000 people

Explanation:

here was an estimated rural population of 3,000 to 4,000 in a 476-square-kilometer (184 sq mi) area of the Copán Valley, giving an estimated total population of 18,000 to 25,000 people in the valley during the Late Classic period.

offline recommendation systems option b

because recommendation systems produce a list of two ways

1. through collaborative filtering

or

2. through content-based filtering