In an ideal OP-AMP, which one is correct? 

The ideal op-amp has the following characteristics:

• Input impedance (Differential or Common-mode) = Infinity
• Output impedance (open loop) = 0
• Voltage gain = Infinity
• Infinite Bandwidth
• Common-mode voltage gain = 0
• Vout = 0 when both inputs are at the same voltage, i.e. (zero "offset voltage")
• Output can change instantaneously (Infinite Slew Rate)
• The purpose of bias current is to achieve the ideal behavior in op-amp which is high CMRR, high differential gain, and high input impedance