How would you describe a material that is "porous"?

A material described as "porous" is characterized by having numerous small openings, or pores, throughout its structure. These pores allow fluids or gases to pass through, making the material permeable to certain substances. This is a defining trait of porous materials, which can include things like sponge, certain types of rock, or biological tissues.

In contrast, the other choices describe materials that are solid or dense, lacking any openings or gaps. A completely solid material would not allow for any fluid movement, while dense blocks are typically impervious to gases and liquids. The presence of pores distinguishes a porous material from these solid structures, emphasizing its ability to absorb or transmit substances.