Which one of the following statements is correct?

• A
  Hybrid orbitals do not form $\sigma$ bonds
• B
  Lateral overlap of $p$-orbitals or $p$- and $d$-orbitals produces $\pi$-bonds
• C
  The strength of bonds follows the order $\sigma_{p-p} < \sigma_{s-s} < \pi_{p-p}$
• D
  $s$-orbitals do not form $\sigma$ bonds