Jamal is testing the effect of four different fertilizers on a particular plant. for his experiment, jamal obtained twenty identical plants. he placed the plants in identical pots, exposed them to the same amount of sunlight each day, and gave them the same amount of water. every week for twelve weeks, jamal gave the plants equal amounts of fertilizer. four plants received fertilizer w, four plants received fertilizer x, four plants received fertilizer y, four plants received fertilizer z, and four plants didn't receive any fertilizer at all. at the end of each week, jamal measured the height of each plant and recorded his data in a table. his data for week five appears below. fertilizer trial 1 trial 2 trial 3 trial 4 none 7 cm 8 cm 8 cm 7 cm w 8 cm 7 cm 8 cm 7 cm x 10 cm 12 cm 11 cm 10 cm y 5 cm 6 cm 5 cm 5 cm z 10 cm 4 cm 7 cm 9 cm at the end of week five, jamal concluded that fertilizers x and z improved the growth rate of his plants. which trials led jamal to this conclusion? a. trials 1 and 4 for fertilizer x and all trials for fertilizer z b. trials 2 and 3 for fertilizer x and trials 1 and 4 for fertilizer z c. all trials for fertilizer x and trials 1 and 4 for fertilizer z d. all trials for both fertilizer x and fertilizer z