20 Jan 2021 / 09:01 H. By Dhara Ranasinghe and Saikat Chatterjee LONDON, Jan 20 (Reuters) - China's $16 trillion sovereign debt market is the proverbial elephant in the investment room. But it's becoming too big to ignore, even for the most risk-averse Western investors. A large, A+ rated market that pays 3% yields, with minimal volatility? It's looking increasingly alluring for European pension funds swimming in sub-zero bond yields as aging populations stretch their finances. For some, the benefits are beginning to outweigh the political risks, and they are upping allocations to China, or ...