thE ExpErimEnt on thE DEntAl pAtiEnts holDing A ruBBEr BAll wAs to sEE _____.
A．iF thE BAll woulD hElp thEm ovErComE thEir strEss
B．iF thE BAll woulD intErFErE with thE DEntist's ACtivitiEs
C．iF thE BAll woulD hElp thE DEntist's trEAtmEnt on thEm
D．on whiCh siDE thEy hElD it.