The basic pattern of blood flow from the lungs to the rest of the body is: pulmonary vein; left ventricle; left atrium; vena cava.
O pulmonary artery; left atrium; left ventricle; aorta.
O vena cava; aorta; right ventricle; right atrium.
O pulmonary vein; left atrium; left ventricle; aorta.

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?