The bond dissociation of the molecules ${\mathrm{A}}_2$, ${\mathrm{B}}_2,{\mathrm{C}}_2$ are $498,158,945 \mathrm{kJ}/$mole respectively. If so, the correct decreasing order of their bond orders is

If bond dissociation energy is more, then bond order will be more. Because more energy is required to break bonds of high bond order.
So bond dissociation energy order is ${\mathrm{C}}_2>{\mathrm{A}}_2>{\mathrm{B}}_2$
Similarly decreasing order of bond order is ${\mathrm{C}}_2,{ \mathrm{A}}_2,{ \mathrm{B}}_2$

Hence, the correct option is (C) .