In a school, the following codes were used during physical exercise. '1' means 'start walking', '2' means 'keep standing', '3' means 'start running at the same spot', '4' means 'sit down'. How many times will a student who performs the following sequence without error from the beginning to the end have to sit down ? 1 2 3 4 2 3 1 4 4 3 2 2 1 2 4 3 1 4 4 1 2
Answer: C. 4
Clearly, the student will have ti sit down at the places marked by boxes : 1 2 3 4 2 3 1 4 4 3 2 2 1 2 4 3 1 4 4 1 2