Out of the given four waves (1), (2), (3) and (4)

$\mathrm{y}=\mathrm{asin}(\mathrm{kx}+\mathrm{\omega t})$       ......(1)
$\mathrm{y}=\mathrm{asin}(\mathrm{\omega t}-\mathrm{kx})$       ......(2)
$\mathrm{y}=\mathrm{acos}(\mathrm{kx}+\mathrm{\omega t})$      ......(3)
$\mathrm{y}=\mathrm{acos}(\mathrm{\omega t}-\mathrm{kx})$      ......(4)
emitted  by four different sources S₁, S₂, S₃ and S₄ respectively, interference phenomena would be observed in space under appropriate conditions when

• A

  Source S₁ emits  wave (1) and S₂ emits  wave (2)

• B

  Source S₃ emits wave (3) and S₄ emits wave (4)

• C

  Source S₂  emits wave (2) and  S₄ emits wave (4)

• D

  S₄  emits waves (4) and  S₃ emits waves (3)