The correct answer is A. Steady state value of the system output.
The final value theorem is a method for finding the steady state value of a system output. It is based on the fact that the steady state value of a system output is equal to the limit of the output as time approaches infinity.
The initial value theorem is a method for finding the initial value of a system output. It is based on the fact that the initial value of a system output is equal to the limit of the output as time approaches zero.
The transient behavior of a system output is the behavior of the output before it reaches its steady state value. The transient behavior is often characterized by oscillations or overshoots.
The final value theorem is not used to find the initial value of the system output or the transient behavior of the system output.