The best answer is c - a hickory tree.
An organism is defined as a living thing which can function on its own. It has interdependent parts and is capable to some degree of responding to stimuli, can reproduce, grow and develop and maintain homeostasis. Plants are organisms because they fulfill all these characteristics.
On organism is made up of one or more cells. If it has only one cell it is called a unicellular organism and if it has more than one cell it called a multi cellular organism.
