First answer Part A then Part B
(Part A) What do scientists use to listen for signs of life that some people believe might exist on distant planets?
A. Global Positioning Systems
B. sextants
C. radio telescopes
D. the Hubble Space Telescope
(Part B) When you jump, you always come back down to Earth. What causes that?
A. gravity
B. tilt
C. orbit
D. rotation