Final answer:
The resultant velocity with which the boat moves is approximately A) 6.67 m/s.
Step-by-step explanation:
To calculate the resultant velocity with which the boat moves, we can use vector addition. The boat's velocity can be broken down into two components: one parallel to the river flow and one perpendicular to it. The parallel component of the boat's velocity is given by Vparallel = Vboat * cos(θ), where Vboat is the boat's speed in still water and θ is the angle between the boat's direction and the river flow.
The perpendicular component of the boat's velocity is given by Vperpendicular = Vboat * sin(θ).
The resultant velocity of the boat is then calculated as Vresultant = sqrt(Vparallel2 + Vperpendicular2).
Plugging in the given values: Vboat = 5.87 m/s and θ = 59.0°, we can calculate the resultant velocity to be approximately 6.67 m/s.