(Q).
Q: What's the best way humans can conserve water? Choices: - boil it - use more - salt it - use less A:
(A).
use less

(Q).
Q: Chemical reactions always involve what? Choices: - fuel - heating - physical change - energy A:
(A).
energy

(Q).
Q: How long can a large star be on the main sequence stage? Choices: - 3 million years - 200.4 million years - 60.11 million years - 10 million years A:
(A).
10 million years