Last answer was wrong, can you please send me the correct answer for this. thank you

$5-$Screw Design for Swivel Hook

The steel crane hook as shown in the following figure is rated at $\backslash ($ P$=3\backslash$mathrm$\{$kN$\}\backslash ).$

The ball$-$thrust bearing allows rotation of the hook for positioning the load. The lower race of the bearing and a third $($bottom$)$ ring have matching spherical surfaces to allow self$-$alignment of the hook with the bearing load. Usually, bearing size selected for a given load and service has internationally standardized dimensions.

Both the threaded portion of the shank or bolt and the nut are made of M$12\backslash (\backslash$times $1\mathrm{.}75\backslash )$ class $5\mathrm{.}8$ rolled coarse threads. A stress concentration factor of $\backslash ($ K$\_\{$t$\}=3\mathrm{.}5\backslash )$ and a safety factor of $\backslash ($ n$=5\backslash )$ are used for threads.

h$.$ Determine the necessary nut length $\backslash ($ L$\_\{$n$\}\backslash ).$