Two coherent sources $P$ and $Q$ produce interference at point $A$ on the screen,where a dark band is formed between the $4^{\text{th}}$ and $5^{\text{th}}$ bright band. The wavelength of light used is $6000 \text{ Å}$. The path difference between $PA$ and $QA$ is:

• A
  $3.6 \times 10^{-4} \text{ cm}$
• B
  $3.2 \times 10^{-4} \text{ cm}$
• C
  $2.4 \times 10^{-4} \text{ cm}$
• D
  $2.7 \times 10^{-4} \text{ cm}$