Oil is immiscible in water, i.e. it does not dissolve in water. Moreover, oil is lighter than water and floats on top of the water surface. Let us look at each of the models in detail and assume from the given illustrations that dark particles are oil and colorless particles are water molecules:
Model 1: water and oil molecules are separated and do not mix with each other. This model best represents the immscible nature of oil in water.
Model 2: Only water molecules are there and no oil can be seen. This model does not fit the properties of oil.
Model 3: Oil is dissolved in water and here we have a water-oil mixture. This does not conform to the properties of oil.
Model 4: Some independent water molecules are there, while the rest are mixed with oil, again not possible due to the immiscible nature of oil.
Hence Model 1 fits the description of a water oil mixture.