b.cellular membranes is the answer
Level 1 - Cells.
Level 2 - Tissues.
Level 3 - Organs.
Level 4 - Organ Systems.
Level 5 - Organisms.
Answer:
Redox reaction may be defined as the reaction in which both the oxidation and reduction reaction takes place. Redox reaction also occurs inside the living organism.
In redox reaction, the one element gains oxygen or loss hydrogen molecule. The other element losses oxygen or gain hydrogen in the reaction reaction. One molecule gets oxidize while the other molecule may get reduced in the redox reaction.
I think the correct answer would be D. In the process of petrification, a tree burning is not included. Petrification is a process that involves organic materials turning into fossils by replacing the original contents of a certain object with minerals.