Question

The expected order of the strength of the $\sigma$-bond is
(1) $p-p$>$p-s$>$s-s$
(2) $s-s$>$p-p$>$p-s$
(3) $s-s$>$p-s$>$p-p$
(4) $p-s$>$s-s$>$p-p$