ACCorDing to thE pAssAgE, Down shiFting EmErgED in thE u.s. As A rEsult oF ______.
A．thE quiCk pACE oF moDErn liFE
B．mAn's ADvEnturous spirit
C．mAn's sEArCh For mythiCAl ExpEriEnCEs
D．thE EConomiC situAtion