Step 1: State the concept.
The Hydrophilic-Lipophilic Balance (HLB) scale runs roughly from $0$ to $20$ and tells us how water-loving or oil-loving a surfactant is. A high HLB means strongly hydrophilic (water soluble).
Step 2: Identify the surfactant.
Sodium oleate is the sodium salt of oleic acid, an anionic surfactant. Its ionised carboxylate head group is strongly hydrophilic, while the hydrocarbon tail is lipophilic.
Step 3: Predict the HLB band.
Because the charged head dominates, sodium oleate is highly water soluble, behaving as a solubiliser or detergent. Such surfactants fall in the HLB band of about $15$ to $20$.
Step 4: Eliminate the low values.
Option 1 (approx $3.0$) describes a water-in-oil emulsifier or antifoam, which does not fit a water-soluble soap, so it is rejected. Option 2 (around $10.0$) is a mid-range oil-in-water emulsifier, still too low.
Step 5: Eliminate the impossible value.
Option 4 (approx $40.0$) lies outside the standard $0$ to $20$ HLB scale and is not valid.
Step 6: Conclude.
The value that fits a strongly hydrophilic anionic soap is around $18.0$, which is option 3.
\[ \boxed{\text{Option 3: Around } 18.0} \]