_____ is a primary tissue that is composed of cells, ground substance and fibres

The correct term that fills in the blank is "Connective Tissue."

Connective tissue is one of the four primary types of tissues in the body, which also include epithelial, muscle, and nervous tissues. It is unique in that it consists of a diverse array of cells, a matrix composed of ground substance (which can be liquid, gel-like, or solid), and fibers (such as collagen and elastin) that provide structural support and elasticity. Connective tissue serves many functions, including binding organs together, providing support and protection, storing energy, and participating in immune responses. Examples of connective tissues include bone, cartilage, adipose (fat) tissue, and blood.