Directions: Choose the appropriate option and fill in the blanks.

After a lot of very serious, expensive and ________ laboratory research involving, for instance, telomeres in the chromosomes of certain cells, scientists have ________ there is a link between stress and aging.

The first blank must be in tandem with 'serious' and 'expensive'. Hence, 'arcane' and 'esoteric' are synonyms, meaning understood by only a few, fits our prediction for first blank. 'Deferred' means postponed, hence would not give sense to the second blank, as scientists have discovered something. Hence, (4) is the answer.