When three airbursts and one graze burst are spotted, what is the HOB correction?

When observed airbursts and a graze burst occur, the Height of Burst (HOB) corrections are critical to ensure accurate targeting. In this situation, three airbursts indicate that the rounds are exploding in the air, which is generally preferred for maximum effect on targets such as personnel or light fortifications. The presence of one graze burst suggests that one round impacted at or near ground level.

If the situation presented indicates that three airbursts have occurred without significant over-targeting or under-targeting, it implies that the adjustment for HOB may not be necessary, as the airbursts are already effective. Therefore, no correction is required because the bursts are ideally positioned to achieve the intended effect.

The other options indicate varying degrees of correction upward, suggesting an assumption of needing to adjust for ineffective targeting or to improve impact positioning. However, the nature of the observed bursts in this scenario suggests that the existing pattern of explosions is satisfactorily achieving the mission's objectives, hence confirming that no adjustment is necessary.