Question

The human heart is an organ that is made up of cells. Not all of the cells that make up the heart are identical, however. What name is given to a group of similar cells that perform a special function and together make up an organ?
A) embryo
B) organelle
C) system
D) tissue

Answer 1

I'm gonna say tissue 

Answer 2

D tissue, A group of atoms create a molecule, a group of molecules creates cells, cells create tissues, and so on.