73. Student Henry is a top gymnast. In order to improve his performance in the competition,
he will perform relaxation training before the competition. What is the change of his
brain waves at the time?
(A) Alpha waves in the brain rise, and β waves fall
(B) Alpha waves in the brain fall, and β waves fall
(C) Alpha wave in the brain goes down, β wave goes up
(D) Alpha wave in the brain goes up, β wave goes up