For the last question it's either C or D.
Methods or procedures that are used to study living things.
Your answer is C.
Not all systems perform the same function or use the same organs.
Battery acid is acidic in nature so its pH will be more.if we add a base its acidity level decreases and it becomes a poor acid. here water acts as a base to decrease the pH value and acidic nature of a acid substance that is battery acid.
