Which one is the essential of Tuiba Shangqiao?
选项：

A:When pushing against each other, the amount of force exerted should be appropriate. Avoid sudden exertion of force during the pushing and pulling.
B:Lift with upward palms,cross palms and separate hands outwards
C:Concentrate strength on arms ,push forward
D:Slowly raise the arms with straight elbows, push forward arms and squat down, pull back with strength, and then stand up.