Which one of the following is not true regarding the Hao Hao Movement in Vietnam?
A. It criticised useless expenditure and sale of child brides
B. It opposed gambling and use of alcohol
C. It motivated the Vietnamese to kill Catholic Missionaries
D. Its founder was Huynh Phu So.

Hint: From the 1$8^{th}$ century many religious movements were hostile to the Western presence such as the introduction of Christianity by French missionaries. Many popular religions in Vietnam were spread by people who believed in the supernatural. Some of these religious movements favoured the French while others inspired movements against them, one such was the Hao Hao movement.

Complete answer: The Hao Hao movement began in 1939 and gained great popularity In The Mekong delta area. The movement drew on religious ideas that were popular in anti-French uprisings in the 1$9^{th}$ century. The founder of the movement was Huynh Phu So. He was popular in Vietnam for performing miracles and helping the poor. He criticized the useless expenditure which gained him a wide appeal. Apart from this, he opposed the sale of child brides, the use of alcohol and opium and gambling. The French tried to suppress the movement by declaring him insane and put him in the mental asylum. The doctor who was given the task to prove him mad became his follower and finally in 1949, declared him sane. The French authorities exiled him to Laos and sent his followers to concentration camps.
Therefore, it's clear that the incorrect statement is Option-C, as he never encouraged his followers to kill Catholic missionaries.

Note: Vietnamese religious beliefs were based on the mixture of Confucianism, Buddhism and local beliefs. The scholars’ revolt in 1868 was against French control and the spread of Christianity. It was led by officials at the imperial court who were angered by the spread of Christianity and French power and it gave rise to the general uprising in the Ngu An and Ha Tien provinces where thousands of Catholics were killed.