Answer:
The correct answer would be D) tissue.
In biology, the level of organisation from simplest to complex level can be summarized as:
Organelles → cells → tissues → organs → organ systems → organisms → populations →communities → ecosystem → biosphere.
It is clear that tissue is organization level that exists between cells and organs.
When similar cells are assembled together to perform specific function, the assembly or this organization is said to be the tissue.
There can be different types of tissues such as muscle tissue, nerve tissue et cetera.
Similarly, tissues arrange themselves to carry out specific function in the form of organ.
For example, heart is made up of cardiac tissue.
