Consider a series of molecules in which the c atom is bonded to atoms of second-period elements: c-o, c-f, c-n, c-c, and c-b. place these bonds in order of decreasing bond length.

Explanation:

As we move along to the right in the same period, the electronegativity and the effective nuclear charge values are higher.

The tendency is that the higher these values are, the shorter the bonds will be.

With that information in mind, and looking at the periodic table, the order would be:

Where the C-F bond is the shortest among them.

i think   the answer is c hope i'm right