thE ExprEssion" A vAriEty oF tEsts" (linE 1, pArA. 3) mEAns ______.
A．A lArgE numBEr oF DiFFErEnt tEsts
B．A lArgE numBEr oF EAsy tEsts
C．A lArgE numBEr oF similAr tEsts
D．A lArgE numBEr oF DiFFiCult tEsts