Which of the following is not a variable in an investigation designed "how much light is needed for a spider plant to grow?"

Question

A.type of plant
B.amount of water
C.source of light
D.amount of light
B?

Which of the following is the best investigation question?
A.Do heavier rocks fall faster than light rocks?
B.Why is the sky blue?
C.Which paper towel is better?
D.What is the best fertilizer for all plants?
B?

Answer 1

For the 2nd one I think it's B or A