Which describes the variable that is changed to test the prediction

Sara goes on a slingshot ride in an amusement park. she is strapped into a spherical ball that has a radius 3*10^2 of centimeters. what is the volume of air in the spherical ball? use this formula: volume of a sphere=4/3pi,r^3 , where r is the sphere’s radius.

The science for classifying and naming organisms is known as

Which kind of worm has a closed circulatory system? a planarian b fluke c pinworm d an earthworm