Holding the passport of what country would enable you to visit the most people without a visa?
Good guess on China, and you’re on the right track, but no. A Chinese passport doesn’t actually get you into that many places.
It is ether that or a British passport.
The UK gets you into a lot of countries, but it doesn’t get you into China.
It’s a country that gets visa free access to China.
A Japanese passport will get you into the homelands of over four billion people.
Singapore is a close second.