In what country do nearly 40% of the citizens have the surname 'Nguyen'?

In what country do nearly 40% of the citizens have the surname `Nguyen`?

Here is the question :

IN WHAT COUNTRY DO NEARLY 40% OF THE CITIZENS HAVE THE SURNAME ‘NGUYEN’?

Here is the option for the question :

South Korea
Myanmar
Vietnam
Taiwan

The Answer:

And, the answer for the the question is :

Vietnam

Explanation:

[STC003372] It is thought that the name Nguyen first appeared in Vietnam when the country was occupied by China in the year 111 BC. Families in China were given surnames so that the country’s government could more easily keep track of its people for tax purposes. Despite the fact that the Chinese were not responsible for giving the name Nguyen to forty percent of the population, it is highly likely that the name spread throughout Vietnam because it is traditional for Vietnamese people to change their surnames to demonstrate their allegiance to the current ruling family. The Nguyen Dynasty, which ruled Vietnam until 1945, came to an end that year, but forty percent of the population still remembers and respects them.