thE mAin iDEA oF thE pAssAgE is ______.
A．lAughtEr AnD physiCAl ExErCisE hAvE similAr EFFECts on thE humAn BoDy
B．smilE CAn proDuCE thE sAmE EFFECts As lAughtEr
C．pAin CAn BE rEDuCED By lAughtEr
D．lAughtEr is thE BEst mEDiCinE