Answer: B. Glow-orb.
Explanation: A kenning is a stylistic device, derived from Norse and Anglo-Saxon poetry, that consists in the use of a two-word phrases, in order to describe an object using metaphors. The two parts of the phrase represents the association between the objects or ideas, to form the metaphor. It is also called "compressed metaphor." In the given phrases, the one that is an example of a kenning is "glow-orb."