Superposition and interference

List-I shows four configurations made of straight and semi-circular narrow tubes containing air. A sound wave of wavelength $\lambda=0.29$ m enters these structures at the point $S$ and a sound detector is placed at $D$. Between the points $S$ and $D$, the sound travels only through the tubes. List-II contains the possible smallest values of $l$ (refer to the figures) for which the detector $D$ records maximum amplitude. Ignore effects of sharp corners. [Given $\cos(15^\circ)=0.97$]

Choose the option that best describes the match between the entries in List-I to those in List-II.

The equations of two waves are given by :
$$y_1=5\sin2\pi(x-vt)\ \text{cm}$$
$$y_2=3\sin2\pi(x-vt+1.5)\ \text{cm}$$
These waves are simultaneously passing through a string. The amplitude of the resulting wave is :

Four harmonic waves of equal frequencies and equal intensities $I_0$ have phase angles 0, $\pi/3$, $2\pi/3$ and $\pi$. When they are superposed, the intensity of the resulting wave is $nI_0$. The value of $n$ is

When two progressive waves $y_1=4\sin(2x-6t)$ and $y_2=3\sin\left(2x-6t-\dfrac\pi2\right)$ are superimposed, the amplitude of the resultant wave is