Answering these questions, Dr. Sai Cong Hong, Deputy Director of the Department of Testing and Quality Assurance, Ministry of Education and Training, said: "Candidates study the 12th grade program to participate in the national high school exam. Therefore, even though the civic education exam has expired, students will still follow the knowledge in the textbooks."

Dr. Sai Cong Hong - Deputy Director of the Department of Examinations, Ministry of Education and Training
Regarding the question of choosing all A or B... is it okay?
Dr. Sai Cong Hong also said that in previous years, if you choose all the answers A or B, C, D, it will account for 25% of the score, this year the ratio is not the same. Some answers only account for 10%, some answers account for 30%... Therefore, candidates who only choose one type of answer can still get a zero score.
Thus, according to the official response from the Ministry of Education's leaders, choosing one answer does not violate the exam regulations, but candidates are still at risk of failing because this year the Ministry of Education will no longer allow the distribution rate of this answer to be equal to 25% as in previous years.