Step 1: Pick a point:
At displacement $x$, $E = \tfrac12kx^2$ and $F = -kx$.
Step 2: Eliminate k:
$k = -F/x$. So $E = \tfrac12\left(-\dfrac Fx\right)x^2 = -\dfrac{Fx}{2}$.
Step 3: Rearrange:
$2E = -Fx$, so $\dfrac{2E}{F} + x = 0$, option (B).
Final Answer:
The relation is 2E/F + x = 0.
\[ \boxed{\text{(B) }\dfrac{2E}{F}+x=0} \]