Step 1: Sort liquids by type:
Divide the four liquids into two groups: those that make ions (acids, bases, salts) and those that do not (pure water, sugar, oils).
Step 2: Place each liquid:
Distilled water: pure, so almost no ions. Lemon juice: an acid, so ions. Sugar solution: molecular, so no ions. Kerosene: a hydrocarbon, so no ions.
Step 3: Pick the odd one out:
Only lemon juice sits in the ion group. Ions are the charge carriers in a liquid, so it alone conducts well.
Step 4: Everyday check:
This is why the bulb in a simple circuit glows in lemon juice or salt water but stays off in sugar water or kerosene.
Final Answer:
Only lemon juice has ions, so option 2 is correct.
\[ \boxed{\text{2 (Lemon Juice)}} \]