ACCorDing to ChristophEr mCkAy, thE possiBility oF trAnsForming mArs______.
A．CoulD oCCur only in sCiEnCE FiCtion storiEs
B．will not BEgin For hunDrEDs, EvEn thousAnDs, oF yEArs
C．is ComplEtEly imprACtiCAl
D．CoulD BE stArtED in 40 to 50 yEArs