Step 1: Understanding the Concept:
Compare with the standard form \(y = A\sin(\omega t - kx + \phi)\). The wave speed is \(v = \dfrac\omega k\).
Step 2: Read off the values:
\(\omega = 12\pi\) rad/s and \(k = 0.02\pi\) rad/m.
Step 3: Compute:
\[ v = \frac{12\pi}{0.02\pi} = 600\ \text{m/s} \]
Step 4: Check:
Option (D). The wave travels in the +x direction because the time and position terms have opposite signs. Options (A), (B), (C) would need \(\omega/k\) of 200, 300 or 400.
Final Answer:
v = omega over k = 12 pi / 0.02 pi.
\[ \boxed{\text{(D) }600\ \text{m/s}} \]