thE rEAson why so FEw ArE lEFt-hAnDED ______.
A．hAs nothing to Do with hErEDity
B．rEmAins onE oF thE grEAt unsolvED mystEriEs oF sCiEnCE
C．hAs littlE to Do with thE working oF thEir BrAins
D．is thAt lEFt-hAnDErs ArE mAinly twins