Answer:
Covalent bond.
Step-by-step explanation:
Chemical bond may be defined as the bond present the elements. The different types of chemical bond are covalent bond, ionic bond, vanderwall's interaction and hydrophobic interaction.
The living cells also constitute the chemical bond in their structure. The most stable chemical bond in the living cell is covalent bond. Covalent bond has highest bond enthalpy and hence the most stable chemical bond in the living molecules. Various proteins and other molecule linked together through covalent bond.
Thus, the correct answer is covalent bond.