Question

the heart is an example of which level of organization within an organism? organ tissue

Explanation:

The heart is made up of different types of tissues (such as cardiac muscle tissue, connective tissue etc.) that work together to perform a specific function (pumping blood). An organ is defined as a group of tissues that work together to perform a specific function. Tissue is a group of similar cells that perform a particular function. Since the heart is a collection of different tissues working together (not just a single type of tissue), it is an organ.

Answer:

organ