Answer:
[A]Magnetite (Fe3O4) The most abundant of the basic iron minerals is magnetite. It has a 72.4 percent iron content. Its colour ranges from dark deep brown to blackish, and it is darker than hematite.
[B]Hematite (Fe2O3) is a mineral that contains almost 70% iron. It’s mostly reddish in colour. Hematite can be virtually black and even blue in colour.
[C]Limonite (2Fe2O3.3H2O), often known as brown ore. It’s iron-rich to the tune of 60%. It comes in a variety of colours, ranging from yellow to darker.
[D]Siderite (Fe2CO3) is a mineral that contains around 48 percent iron.
Therefore, [A] magnetite is one of the best iron ores based on iron content.