Chapter 18 - Basic Electric Circuits - Learning Path Questions and Exercises - Multiple Choice Questions - Page 650: 17

(c) $T_{1}=T_{2}$

The time constant of RC circuit is given by $T=RC$. In both cases, the resistor used was the same and the capacitance is the property of the capacitor which is independent of the voltage applied. Thus the time constant will be same for the two cases.