The answer to this question is TRUE.
Rather than simply believing this statement, you can find evidence to support this claim. We can look at the length of various carbon-carbon bond lengths.
In the molecule ethane, we have H₃C-CH₃, with a C-C single bond length of 154 pm.
In the molecule ethene, we have H₂C=CH₂, with a C=C double bond length of 133 pm.
We see from this data that a double bond is shorter than a single bond. Now if we look at the structure of benzene:
H H
C = C
/ \
H-C C-H
\\ //
C --- C
H H
It appears that there are three C=C double bonds and three C-C single bonds. So you would expect different bond lengths between the double and single bonds. However, what we actually find is that every C-C bond is the same length of 140 pm. This is due to resonance, therefore, every C-C bond is actually an average of the double bond character and single bond character each bond experiences which gives us a value of 140 pm which is longer than a traditional C=C bond and shorter than a traditional C-C bond.