Step 1: Concept Identify the orientation of the ellipse by comparing denominators $a^2$ and $b^2$.
Step 2: Meaning $a^2=9$ (under $x$) and $b^2=4$ (under $y$). Since $a > b$, the major axis is horizontal.
Step 3: Analysis For a horizontal major axis, the equation is $y = k$, where $(h,k)$ is the centre.
Step 4: Conclusion The centre is $(1,6)$, so the equation of the major axis is $y=6$.
Final Answer: (B)