Which of the following liquids is the most viscous?

The most viscous liquid among the options provided is molasses. Viscosity is a measure of a fluid's resistance to flow; higher viscosity means a thicker fluid that flows more slowly.

Water is known for its low viscosity; it flows easily due to its molecular structure. Milk, while slightly thicker than water due to the presence of fats and proteins, is still relatively fluid compared to more viscous substances. Olive oil falls in between water and molasses in terms of viscosity, but it is still much thinner than molasses.

Molasses, on the other hand, is a thick syrup that is a byproduct of sugar production. Its complex sugar composition and higher density contribute to its high viscosity, making it significantly thicker than the other liquids listed. This characteristic means that molasses will pour and flow much more slowly than water, olive oil, or milk, confirming it as the most viscous option.