Middle lamella is mainly composed of :

The correct option is A Calcium pectate
Middle lamella is a thin, amorphous and cementing layer between two adjacent cells. Middle lamella is the first layer which is deposited at the time of cytokinesis. It is just like brick work of common wall between two adjacent rooms. Middle lamella is absent on the outer side of surface cells. It is made up of calcium and magnesium pectates. The softening of ripe fruits is caused by partial solubilisation of pectic compounds to produce jelly-like consistency.