Which type of nebula is characterized by a high density of dust that blocks light?

The correct response identifies a dark nebula, which is characterized by its high density of dust and gas that effectively blocks light from objects behind it. In contrast to other types of nebulae, dark nebulae do not emit light or reflect it; therefore, they appear as dark patches against the brighter background of stars and other astronomical features. This opacity is primarily due to the thick concentration of interstellar dust particles, which absorb and scatter light, preventing it from passing through.

Other types of nebulae, like bright nebulae or emission nebulae, are typically involved in light emission due to ionized gas, while planetary nebulae usually display bright, glowing shells around dying stars. In summary, the defining characteristic of dark nebulae is their ability to obscure light, which is a critical feature that sets them apart from other nebula categories.