Question on: JAMB Biology - 2014

The correct answer is A. Heart, because it is the most complex organ among the options. * **Heart:** A heart is a complex organ composed of multiple tissues (muscle, connective, nervous, etc.) that work together in a coordinated manner to perform a specific function (pumping blood). It is an organ-level of organization. * **Hair:** Hair is a tissue composed primarily of dead cells. It is a tissue-level of organization. * **Euglena:** Euglena is a single-celled organism (a protist). It exhibits a cellular level of organization. * **Hydra:** Hydra is a simple multicellular organism that has tissues and some simple organs, but it is not as complex as the heart. It is an organ-level of organization. The cellular levels