Fluorine (F2), Chlorine (Cl2), Bromine (Br2), Iodine (I2) are called halogen compounds, they occur as diatomic molecules in which a covalent bond is formed after sharing 1 electron with each other. As it moves down from chlorine to iodine in the halogen group, the atomic size increases, and hence bond length also increases.
As bond length increases, the energy required to break bonds (dissociation energy) decreases.
So, chlorine will have the highest bond energy.