Correct Answer  Option 2 : Transient stability
Transient stability: Transient stability is the ability of the power system to maintain synchronism when subjected to a severe transient disturbance.
Transient stability of the system can be improved by
 Increasing the system voltage
 Increase in the X/R ratio
 Using highspeed governors on machines
 Series capacitance
 Excitation control
 Highspeed circuit breakers help to clear the fault as quickly as possible
 By turbine fast valving
 Highspeed excitation
 Use of auto reclosing breakers
 Some of the other ways to improve the transient stability are by employing lightning arresters, high neutral grounding impedance, single pole switching, quick Automatic Voltage Regulators (AVRs).
Steadystate stability limit = \(\frac{{{V_1}\;{V_2}}}{X}\)
More steadystate stability represents more transient stability of the system.
Steadystate stability limit of the system can be increased by the following methods:

Upgrading voltage on the existing transmission system or opting for higher voltages on the new transmission system.

The use of an additional parallel transmission line reduces transfer reactance X, thereby increases it.

The use of a transformer with lower leakage reactance improves a steadystate stability limit.
 Series capacitive compensation of transmission line reduces transfer reactance X and hence steadystate stability limit increases.

The use of bundled phase conductors reduces the reactance thereby increasing the stability limit.