The passage from "Mowgli’s Brothers" in The Jungle Book outlines specific rules regarding the behavior of wolves in relation to their familial obligations to the pack. The law states that wolves can withdraw from their pack when they marry, but they must present their cubs to the Pack Council for identification once the cubs are old enough.
Given this context, the most relevant interpretation related to Mowgli is:
Mowgli will have to be revealed to the pack.
As Mowgli is raised by wolves and is considered part of the pack, there will come a time when he too will need to be part of the identification process in accordance with the laws of the jungle. The other options do not accurately reflect the implications of the law as it pertains to Mowgli's situation.