Star formation, formation of planets, and our solar system

Correct answer: B. Dust and rocks containing iron oxide

The correct answer is B. Mars appears reddish because iron-bearing minerals in its surface rocks and dust have oxidised, producing iron oxides, commonly described as rust. Fine iron-oxide dust is lifted and spread across the surface and atmosphere, so it gives the planet a strong red or orange appearance when viewed from space. Mars does not owe its colour to a blue methane layer, liquid gold, or dense clouds. In fact, Mars has a thin atmosphere and is not covered by a permanent dense cloud layer like a gas giant. The key scientific association for examination purposes is Mars, iron minerals, oxidation, and red dust.