Only 1- the experiment can not show a cause and effect relationship if there are more than one factors contributing to the outcome.
C.Xylem
Xylem is where the nutrients and water gets transported upward
B. Gene. Piebalding is caused by mutant copies of genes.
Answer:
<em>Plants give out carbon dioxide not only at night but during the day too. It happens because of the process of respiration in which plants take in oxygen and give out carbon dioxide. As soon as the sun rises another process called photosynthesis starts, in which carbon dioxide is taken in and oxygen is given out</em>
