The correct option is B Two C−F bonds attached to the middle carbon atom are longer as compared to the other C−F bonds at the terminal carbons
According to Bent’s rule, the most electronegative elements tend to occupy the orbitals that has less s-character.
In the above molecule, though it is sp3 hybridized, because of the electronegative nature of F, the C−F bonds have more p-character and C−C bonds have more s-character. Greater the p-character, greater is the bond length. In the above molecule, in the terminal C−F bonds, the p-character is shared by 3 C−F bonds, whereas in the middle C−F bonds the p-character is shared by only two C−F bonds. Hence, the middle C−F bonds are longer than the terminal C−F bonds because p-character per C−F bond will be greater.