Using horizontal strips, the area bounded by the curve $x = g(y)$, the $y$-axis and the lines $y = c$ and $y = d$ is given by which integral?

1. A horizontal elementary strip has width $x = g(y)$ and thickness $dy$, so $dA = x\,dy$. 2. Summing from $y = c$ to $y = d$ gives $A = \int_c^d x\,dy = \int_c^d g(y)\,dy$. 3. The variable of integration is $y$, ruling out forms written in $x$. _Source: NCERT Class 12 Mathematics Ch 8 "Application of Integrals", p.2_