JEE Main 2023 Physics question

A single slit of width 'a' is illuminated by a monochromatic light of wavelength 600 nm. The value of 'a' for which first minimum appears at = 30° on the screen will be :

• (A)1.2 mCorrect
• (B)3 m
• (C)1.8 m
• (D)0.6 m