$\frac{\lambda \times 3}{4}=1.2$
$\lambda=1.6 \mathrm{m}$
so pressure is maximum at $\frac{\lambda}{4}=0.4 \mathrm{m}$ from the open end
$(A)$ $u=0.8 v$ and $f_5=f_0$
$(B)$ $u=0.8 v$ and $f_5=2 f_0$
$(C)$ $u=0.8 v$ and $f_5=0.5 f_0$
$(D)$ $u=0.5 v$ and $f_5=1.5 f_0$
