Absolute phrases are types of phrases which don't refer to just a single word in a sentence, but rather to the entire sentence. Usually, they have this form: noun + participle (looks like a verb ending in -ing) + optional modifiers/objects.
In this sentence, just look for a participle in order to find your absolute phrase. The correct answer is eyes glittering with concentration. The phrase describes how Jacques managed to move his cursor.
B. It helps readers understand the princess's love for the young man and D. It allows readers to determine how the story might end.