About three-quarters of the surface of which planet is covered by iron oxide dust?

The correct answer is Mars because it is widely recognized for its distinct reddish appearance, which is primarily due to the presence of iron oxide, commonly known as rust, on its surface. This iron oxide dust covers a significant portion of the planet, contributing to its nickname, the "Red Planet." The composition of Martian soil and dust has been extensively studied through various missions and rovers, confirming that the iron-rich materials are responsible for this coloration.

Other planets listed have different surface compositions and characteristics. Venus has an atmosphere dominated by thick clouds of sulfuric acid, and its surface is concealed from view, making it difficult to identify similar coverage by iron oxide. Earth, while it does have iron in its composition, has a diverse surface with water, vegetation, and urban areas that obscure the presence of iron oxide dust. Mercury's surface is rocky and heavily cratered, with little to no atmosphere to support the widespread distribution of iron oxide in the form of dust. Thus, Mars stands out distinctly with around three-quarters of its surface covered in iron oxide.