- One of them (b) is organisation-based and a clear candidate for UTC.
- Two of them (a and c) are for events that are local to a network and the network has it's own timezone.
- One (d) is a log that is based on a Meraki network but he events can relate to any timezone because the devices are roaming, This would also be a candidate for UTC.
With (a) and (c) ruled out there it is 50:50 chance and my guess (based on what is more likely) would go to (b).