The correct answer is (a) 5.
The question is asking for the value of $n$ in the following equation:
$$P_n = \frac{1}{3}P_{n-1}$$
We can solve this equation by starting with $P_0 = 1$ and then repeatedly substituting the previous value of $P_n$ into the equation. This gives us the following sequence:
$$P_0 = 1$$
$$P_1 = \frac{1}{3}P_0 = \frac{1}{3}$$
$$P_2 = \frac{1}{3}P_1 = \frac{1}{9}$$
$$P_3 = \frac{1}{3}P_2 = \frac{1}{27}$$
$$P_4 = \frac{1}{3}P_3 = \frac{1}{81}$$
As you can see, the sequence is decreasing by a factor of $\frac{1}{3}$ each time. This means that the value of $n$ must be a multiple of
42.9-11.4 132.3-11.4 132.3s0 89.4 11.4 132.3c6.3 23.7 24.8 41.5 48.3 47.8C117.2 448 288 448 288 448s170.8 0 213.4-11.5c23.5-6.3 42-24.2 48.3-47.8 11.4-42.9 11.4-132.3 11.4-132.3s0-89.4-11.4-132.3zm-317.5 213.5V175.2l142.7 81.2-142.7 81.2z"/> Subscribe on YouTube