Sarah performs an experiment to determine the effect of nitrogen on plants. She studies the effect of nitrogen on the growth of the root hair, height of the plants, and nodule formatoon. Which factor is a independent variable?

Which statement does lola need to correct, and why? a) statement 1 because spiral galaxies do not havearmsb) statement 2 because the bulges contain mostlyyoung red stars.c) statement 3 because the arms are made of mostlyyoung blue and blue-white stars.d) statement 4 because spirals galaxies contain littleto no dust.(c)