Final answer:
The adverb in the sentence is instantly, which provides information about how Leonardo solved the mystery.
Step-by-step explanation:
The adverb in the sentence is instantly. Adverbs modify verbs, adjectives, or other adverbs and provide more information about time, manner, place, frequency, or degree. In this sentence, the adverb instantly tells us how Leonardo solved the mystery, indicating that it happened without any delay.
Learn more about Adverbs