Progressive Wave Equation question from JEE Main 2021 (24 Feb, Shift 2)

Answer: (c)

1. A travelling wave has the form $f(kx \pm \omega t)$, a single function of a combination of $x$ and $t$.
2. $A\sin(15x - 2t)$ has this form, moving along $+x$ with $v = \dfrac{2}{15}$.
3. $A\sin x\cos\omega t$ is a stationary wave; the others do not depend on $x$ and $t$ only through $(x \pm vt)$.
4. So the answer is (c) $y = A\sin(15x - 2t)$.