Mr. greenjeans wants to know which fertilizer grow the biggest pumpkins. he plants three pumpkin seeds of the same variety and then uses three different types of fertilizer on the three seeds. the seeds receive the same amount of fertilizer, water and sunlight. mr. greenjeans monitors the pumpkin seeds' growth for three months.
how could mr. greenjeans improve his experiment?
a) mr. greenjeans needs a control group for comparison.
b) mr. greenjeans should use corn and radish seeds as a comparison.
c) mr. greenjeans should use three different types of pumpkin seeds.
d) mr. greenjeans probably should monitor the pumpkins for a longer period of time.