Consider the following statements A and B and identify the correct answer : A. Fresnel's diffraction pattern occurs when the source of light or the screen on which the diffraction pattern is seen or when both are at finite distance from the aperture. B. Diffracted light can be used 'to estimate the helical structure of nucleic acids.

• A

  $A$ and $B$ are true
• B

  $A$ and $B$ are false
• Correct answer
  C

  $A$ is true but $B$ is false
• D

  $A$ is false but $B$ is true

Hence, the correct answer is option: 'C'.