A monochromatic laser beam of wavelength \(\lambda\) is normally incident on a single slit. Starting at time \(t = 0\), the slit width \(a\) is expanded continuously from zero at a constant speed \(v\), such that \(a(t) = vt\). A small photodetector is fixed at a small, constant angle \(\theta_0 > 0\) relative to the central axis. Which of the following graphs best represents the light intensity \(I\) recorded by the photodetector as a function of time \(t\)?