Explanation

(b)
According to X-ray analysis all carbon-carbon bond distance $(1.397\mathring{\mathrm{A}})$ are equal in benzene. The bond order of carbon-carbon bond is 1.5 in benzene.
Hence, carbon-carbon bond distance $(1.397\mathring{\mathrm{A}})$ is less than $C - C$ single bond $(1.54\mathring{\mathrm{A}})$ and more than $C = C$ double bond$(1.33\mathring{\mathrm{A}})$.