Which of the following seems to be closest in meaning to the phrase clamping down as mentioned in the passage?

Directions (Q.101 - 105): Read the following passage carefully and answer the questions given below them. Certain words/phrases have been printed in bold to help you locate them while answering some of the questions. Markets regulator Sebi and Indian exchanges need to review their recent decision not to share data with foreign exchanges that trade derivatives on Indian stocks. Simply clamping down on securities data-sharing is no way to prevent the market for Indian underlyings moving abroad. The way forward is to rationalise the rules, transaction costs and trading hours for equity, currency and commodity derivatives products, so as to have a thriving futures and options market here and attendant risk management skills . Securities exchanges are highly networked entities, and it is not in the interest of Indian markets to unilaterally black out data and price discovery with counterparts abroad. It is true that rupee and Nifty derivatives are increasingly traded outside India, but there are network benefits too. Such trading results in global price discovery of the Indian underlyings, and cost-effective hedging of risk for foreign investors in the Indian market, which would very much be in the interest of domestic investors, besides of their foreign counterparts. We do need to review our norms on securities tax, stamp duties, margin requirements, position limits and even participation rules for derivatives, which are now accepted as standard risk-management products globally. Without a thriving derivatives market, we cannot have an attractive bond market and modern, transparent arm’s-length finance. It follows that without modern futures and options markets, the entire economy would be affected. And cutting ourselves off from international markets, by fiat, is atavistic , draconian and a throwback to pre-reform days. In a fast-growing, globalising economy, the gag order on data exchange is incongruous and shakes the confidence of the rest of the world in the Indian economy.