TTL gates operate on a nominal power supply voltage of 5 volts, +/- 0.25 volts. Ideally, a TTL high signal would be 5.00 volts exactly, and a TTL low signal 0.00 volts exactly. However, real TTL gate circuits cannot output such perfect voltage levels, and are designed to accept high and low signals deviating substantially from these ideal values.
Acceptable input signal voltages range from 0 volts to 0.8 volts for a low logic state, and 2 volts to 5 volts for a high logic state.
Reference :Logic Family
So option B is correct.