The bond dissociation energy of  $\mathrm{B}-\mathrm{F}\text{ in }{\mathrm{BF}}_3$ is $646\mathrm{kJ}{\mathrm{mol}}^{-1}\text{ whereas that of }\mathrm{C}-\mathrm{F}\text{ in }{\mathrm{CF}}_4\text{ is }515\mathrm{kJ}{\mathrm{mol}}^{-1}\text{. The }$correct reason for higher B -F bond dissociation energy as compared to that of C — F is 

 smaller size of B— atom as compared to that of C— atom. 

lower degree of $\mathrm{p\pi }-\mathrm{p\pi }$interaction between B and Fin BF₃ than that between C and F in CF₄.

$\mathrm{significant} \mathrm{p\pi }-\mathrm{p\pi } \mathrm{interactionbetween} \mathrm{B} \mathrm{and} \mathrm{F} \mathrm{in} {\mathrm{BF}}_3$ where there is no possibility of such intraction between C and F in CF₄ 

stronger $\sigma$ bond between B and F in  ${\mathrm{BF}}_3$ as compared to that between C and F in CF₄