A student wants to determine if different types of soil, A and B, affect the propagation of African violets. One hundred leaves from the same variety of African violet were selected. The leaves were then randomly assigned to 50 pots with type A soil and the remaining leaves were put into the 50 pots with type B soil. All of the pots were given the same amount of water and arranged in 10 rows of 10 pots near a window for light. The 50 pots with type A soil were placed closest to the window. At the end of two months, the pots with type A soil had the greatest number of pots with new growth, so the student concluded that soil type A was more effective that soil type B. Is this a valid conclusion?

Yes, because the leaves were randomly assigned, this evenly distributed the variability in the leaves; therefore, type A soil is more effective than type B soil.

Yes, because the amount of water and light were controlled, this may have reduced the variability in the response; therefore, type A soil is more effective than type B soil.

No, because the pots with type A soil were closest to the window, they received more light, which may have led to the new growth.

No, because only African violets were used, replication was not properly implemented; therefore, we cannot conclude that type A soil was more effective.