Steady state error is a measure of how well a control system is able to track a desired input signal. It represents the difference between the desired output and the actual output of the system when the input signal has reached a steady state.

In this system, the position error constant Kp is given as 3. The position error constant relates the steady state error to the input signal. It is defined as the ratio of the steady state error to the input signal. Mathematically, Kp = 1 / steady state error.

Given that the input signal is 8tu(t), where u(t) is the unit step function, we can determine the steady state error using the position error constant.

Let's calculate the steady state error step by step:

1. First, we need to determine the Laplace transform of the input signal.
The Laplace transform of tu(t) is 1/s^2.
Therefore, the Laplace transform of 8tu(t) is 8/s^2.

2. Next, we determine the Laplace transform of the steady state error.
Let the Laplace transform of the steady state error be E(s).
Then, E(s) = Kp / (s * 8/s^2) = Kp * s^2 / 8.

3. To find the steady state error, we need to take the inverse Laplace transform of E(s).
Using inverse Laplace transform tables or software, we can determine that the inverse Laplace transform of Kp * s^2 / 8 is Kp/8 * t^2.

4. Since the input signal is a unit step function, the steady state error is the value of the inverse Laplace transform at t = infinity.
Therefore, the steady state error is Kp/8 * infinity^2 = Kp/8 * ∞ = 3/8 * ∞ = 0.

Hence, the correct answer is option 'C', which states that the steady state error is 0.