Question

7

Mark is performing an investigation to determine what type of fertilizer helps a plant grow best. He plants ten plants of the same type
in a garden and gives them all the same amount of water and fertilizer each day. However, he gives each plant a different type of
fertilizer
Which variable in the experiment should Mark control (or keep constant)?
A location of the plants
OB amount of fertilizer given daily
Camount of water given daily
OD all of these
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Answer 1

D, as he is testing which type of fertiliser is the best, and hence it should be the only changed variable. Everything else should remain the same.