The planets known as "terrestrial" planets are which?
a. mercury, venus, earth, and mars
b. mercury, mars, saturn, and jupiter
c. venus, mars, saturn, and neptune
d. jupiter, saturn, uranus, neptune

Which of the following correctly matches an immune system cell with the defense it produces? a. b cells release cytotoxins. b. t cells release cytotoxins. c. b cells absorb antibodies. d. t cells absorb antibodies.