Passage: Tata Sons Limited is the holding company of the Tata Group and holds the bulk of shareholding in these companies. It was established as a trading enterprise in 1868. About 86 % of the equity capital of Tata Sons is held by philanthropic trusts endowed by members of the Tata family. The biggest two of these trusts are the Sir Dorabji Tata Trust and Sir Ratan Tata Trust. Tata Sons is the owner of the Tata name and the Tata trademarks, which are registered in India and several other countries. TCS alone generates 70 % revenues of its parent company, Tata Sons. Natarajan Chandrasekaran took over as Chairman of Tata Sons on 21 February 2017.

Question: Based on this passage, who become the chairmen of tata sons in 2017?
Steam of consciousness below:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
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To answer the above question, the relevant sentence is: Natarajan Chandrasekaran took over as Chairman of Tata Sons on 21 February 2017.
So, the answer is Natarajan Chandrasekaran.