Where did the carbon found throughout the body of a plant originate?

What happens when a magniseum ion ia atracked to a chlrene ion

Me the formula cacl2 represents the compound

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?