A block of mass $m$ initially at rest is dropped from a height $h$ on to a spring of force constant $k$. The maximum compression in spring is $x$ ,then

Question

$$(a)\;mgh=\frac{1}{2} kx^2 \quad (b)\;mg(h+x)=\frac{1}{2}kx^2 \quad (c)\;mgh=\frac{1}{2}k(x+h)^2 \quad (d)\;mg(h+x)=\frac{1}{2}k(x+h)^2$$