During a walk-around inspection of a combination vehicle's coupling system, which of these is something the manual specifically says to check?

Explanation

On the coupling-system walk-around, the manual calls for confirming no gap where the fifth wheel's upper and lower halves meet, locking jaws closed around the kingpin's shank rather than its head, and a release arm properly seated with the safety latch engaged. This is unique, combination-vehicle-specific inspection content required by 49 CFR 383.111(c)(2) as a distinct knowledge area from single-vehicle inspection, though the paragraph itself does not list these specific checks. A welded fifth wheel invents a mounting method the manual doesn't require; 49 CFR 393.70 calls for properly tightened bolts and brackets of adequate size, or another device giving equivalent security, not a specific weld-versus-bolt distinction. A kingpin color-coding scheme does not exist. Landing gear fully lowered describes the opposite of the correct pre-driving state; it should be fully raised, not lowered.

Source: 49 CFR 383.111(c)(2)