The subject "the Indian IT companies" is plural, so it needs a plural auxiliary verb. The present perfect "have gone into" correctly shows a recent shift that still affects the present, which fits the ongoing "stock taking mode" mentioned later.
Since the underlined part already agrees in number and carries the right tense, option A, "no error", is correct.
If the price of a commodity increases by 25%, by what percentage should the consumption be reduced to keep the expenditure the same?