The water having more dissolved O$$_2$$ is:

The solubility of gases in water is governed by temperature: as temperature increases, the solubility of gases decreases (Henry's law and Le Chatelier's principle, since dissolution of a gas is exothermic). Boiling water (100 $$^\circ$$C) and water at 80 $$^\circ$$C therefore contain very little dissolved oxygen. Polluted water typically has a low dissolved oxygen content because organic pollutants consume oxygen during biodegradation.

Water at 4 $$^\circ$$C is cold, and at lower temperatures gaseous oxygen is far more soluble. Among the given options, water at 4 $$^\circ$$C will have the highest concentration of dissolved $$\text{O}_2$$.

The answer is option (4).