Two sources of light of wavelengths $2500 \,\mathring{A}$ and $3500 \,\mathring{A}$ are used in Young's double slit experiment simultaneously. Which orders of fringes of the two wavelength patterns coincide?

• A
  $3^{rd}$ order of $1^{st}$ source and $5^{th}$ of the $2^{nd}$
• B
  $7^{th}$ order of $1^{st}$ source and $5^{th}$ of the $2^{nd}$
• C
  $5^{th}$ order of $1^{st}$ source and $3^{rd}$ of the $2^{nd}$
• D
  $5^{th}$ order of $1^{st}$ source and $7^{th}$ of the $2^{nd}$