Matter that can flow is referred to as-

Matter that can flow is generally referred to as a "fluid". This includes substances such as liquids and gases, which can flow and take on the shape of their container. Unlike solids, which have a fixed shape and volume, fluids can flow and are able to conform to the shape of the container in which they are held.

Both liquids and gases have the tendency to flow due to the kinetic energy in their particles.

Thus, they are jointly called as Fluids.

Hence, the correct option is (A).