Directions: Select the most appropriate filler(s) for the blank(s) such that the sentence makes coherent sense.

The research scholar performed the experiments with ________ and worked ________ to submit an award - winning thesis.

The operative word in this sentence is 'and', which implies that both the words would be conveying that same basic meaning. The clue for this sentence is that research work requires hard work, persistent effort. As 'diligence' means hard work, hence it is ideal for first blank. Moreover, 'assiduously' means with perseverance and care, thereby giving sense to the sentence. Hence, (4) is the answer.