Which of the following improved travel in 1807?
the national road
the steamboat
the steam locomotive
the transcontinental railroad

The steamboat

Explanation:

Robert Fulton collaborated with Robert Livingston in 1807 to build the North River Steamboat. This boat, which later acquired the colloquial name Clermont, became the first ship to show the feasibility of using steam propulsion in commercial water transport. This was something revolutionary that greatly improved and expedited the trips made in 1807.

offline recommendation systems option b

because recommendation systems produce a list of two ways

1. through collaborative filtering

or

2. through content-based filtering

a social contract.

"a social contract is an agreement between citizens and their leader where the citizens give up certain freedoms in exchange for protection. the constitution of the united states is an example of a social contract."