Which of these energy resources might replace dwindling petroleum supplies one day?
a)coal and natural gas,
b)tar sands and uranium,
c)oil shade and tar sands,
d)wind and coal?

Ans.

Level of organization in multicellular organisms, arranged from simplest to most complex as organelles, cells, tissues, organs, organ system, and organism. Liver is an organ as it is made up of various types of tissues, consisted of millions of liver cells or hepatocytes.

Thus, the correct answer is option). 'organ.'