Grade 5 week 8 learning task 1​

Ascience research group is testing a new type of plant food. one trial is conducted in a controlled experiment. the data from the trial show that the plant that received the new food grew faster than the control plant. the group announces that the new plant food makes plants grow faster. what is the main weakness in this scientific claim?

The variation among individuals, on which natural selection acts

The changes that the students observed, rapid breathing and sweating, would be classified as a to a change in a system.