Final answer:
The correct answer is A. matrix. In multicellular organisms, cells interconnect to form tissues which combine to form organs, which in turn make up organ systems. The matrix in connective tissues provides strength and flexibility.
Step-by-step explanation:
The correct answer is A. matrix.
In multicellular organisms, several cells of one particular kind interconnect with each other and perform shared functions to form tissues, several tissues combine to form an organ, and several organs make up an organ system. Several systems functioning together form an organism.
Connective tissues, such as blood, are considered a matrix because they have non-living material that provides strength and flexibility.