Gravity separation technique is a method of separating two components from a suspension or any other homogeneous mixture where separating the components with gravity is sufficiently practical.

Explanation:

Gravity separation technique is based on the difference in the specific gravity or density of the components in the mixture. The principle behind the gravity separation technique is that heavy particles settle down faster than the lighter ones. The process is widely used in the beneficiation of minerals, especially for the separation of ore minerals.

The correct option for the applicability of gravity separation technique is option 'D' i.e. oxide ore. This is because of the following reasons:

- Ore minerals are classified into sulfide, oxide, and silicate minerals.
- The gravity separation technique is less effective for sulfide minerals because of their lower density.
- Carbonate ores are generally not concentrated using gravity separation techniques because they have a similar specific gravity to the gangue mineral.
- Oxide ores, on the other hand, have a relatively low density and are easily separated using gravity separation techniques.

Therefore, the gravity separation technique is mainly applicable to oxide ores. Some examples include:

- Iron ores such as hematite, magnetite, limonite, and siderite
- Tin ores such as cassiterite
- Manganese ores such as pyrolusite and rhodonite
- Tungsten ores such as wolframite and scheelite

In conclusion, the gravity separation technique is a useful method for the separation of minerals based on their density. It is mainly applicable to oxide ores because of their low density.