Why is the gravitational slingshot important to space exploration? A. to allow spacecraft to refuel without stopping
B. to help spacecraft increase velocity without using additional fuel
C. to make spacecraft weightless
D. to make spacecraft safer

B. To help spacecraft increase velocity without using additional fuel

Explanation:

The gravitational slingshot is the use of the gravity of a planet or other astronomical object to alter the path and velocity of a spacecraft. It  also helps slow down a spacecraft, change their orbits into directions they could never reach, or accelerate to high velocities (without using additonal fuel).