Answer:
tissue
Explanation:
The level of organisation of life in biology refers to an hierarchical classification of how organisms are formed beginning from the simplest unit of life, which is a CELL. The cell is the basic unit of life and it represents the least complex level of organization.
However, a collection of cells with similar functions give rise to a TISSUE. Tissues give rise to ORGANS. Organs give rise to ORGAN SYSTEMS. Organ system gives rise to ORGANISM. The order of this hierarchy from the least to most complex is as follows:
Cell → Tissue → Organ → Organ system → Organism
According to the question, the level that is just below organs in complexity is TISSUE.
