Answer:a,b,c,d
Step-by-step explanation:
Cell-cell interaction occurs in multicellular organisms. When two cells are in close approximation they form a tight junction which are multiprotein complexes that provide contact between neighboring cells. This tight junction permit calcium and other small molecules to pass through from one cell to another.
Transmembrane protein serves as ion channels for transport of ions between extracellular and intracellular fluid.
Integral proteins are deeply embedded in the bilayers and are attached by hydrophobic bonds. They contribute to the structural stability of the cell.
Carbohydrates are found on the cell surface bindings to proteins to form glycoprotein. This glycoprotein are excellent in providing an immune response, protection of cell and cell-cell recognition.