Fill in the blank with the most suitable option:
An adverb is a word or phrase that qualifies or changes an adjective, verb or another adverb, to express a relation of a situation, cause etc.
The correct answer is B) as it indicates something contained in the place mentioned.
Options A, C and D cannot be used here as 'therefrom' indicates something a place as a source ,'thereof' indicates something concerning or from something, and 'thereon' indicates something on the thing that has been mentioned respectively.
They found a suitcase full of documents and therein lay the proof of his crime.