= Solution
From the complete <normal mode> result, the <vibrational infrared activity> belongs to
$$
\boxed{\Gamma_{\rm IR}=A_{2u}+3E_{1u}.}
$$
The $A_{2u}$ fundamental couples to the out-of-plane dipole component and each $E_{1u}$ fundamental to the two in-plane components. Counting one frequency for each degenerate pair, the expected number is \b[$1+3=4$ fundamental bands], containing seven vibrational coordinates.
This is the symmetry count for the full molecule, including <hydrogen> displacements. The experimental compilation likewise lists the out-of-plane $A_{2u}$ fundamental and three $E_{1u}$ fundamentals; anharmonic resonances and weak intensity borrowing can produce additional observed features beyond the ideal fundamental count.<Benzene vibrational data in the NIST Chemistry WebBook>[Vibrational energy-level table: A2u row and three E1u fundamentals]{ref}
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