Which of the following describes a viscous substance?

A viscous substance is characterized by having a relatively high resistance to flow. This means that such substances do not flow easily and can be thick or sticky in nature. For example, honey and molasses are commonly cited as viscous liquids because they take longer to pour or spread compared to water, which has a low viscosity and flows easily.

In the context of the other options, a viscous substance is not described by low resistance to flow, as that would imply it moves easily, contradicting the definition of viscosity. Additionally, being completely solid or gas-like in consistency describes states of matter that are quite different from viscosity, which specifically refers to the flow characteristics of liquids. Therefore, the correct answer captures the essential property of a viscous substance effectively.