The transverse displacement $y(x, t)$ of a wave on a string is given by $y(x, t)=e^{-\left(a x^2+b t^2+2 \sqrt{a b} x t\right)}$. This represents a

• Correct answer
  A

  wave moving in $-x$ direction with speed $\sqrt{\frac{b}{a}}$
• B

  standing wave of frequency $\sqrt{b}$
• C

  standing wave of frequency $\frac{1}{\sqrt{b}}$
• D

  wave moving in $+x$ direction with $\sqrt{\frac{a}{b}}$

Hence, the correct answer is option: 'A'.