Direction: Spot the grammatical errors in the given sentence. Mark the part with error as your answer. If there is no error, mark "No error" as the answer. (Ignore punctuation error)

Experts believe that a (a)/ gradually decreasing infant mortality rate (b)/ is lead to a proportionate (c)/ decrease in the size of our brains. (d)/ No error (e)

[BANK OF BARODA (PO), 2011]